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Previously, we showed the human erythrocyte cytoplasmic endoskeleton composed of actin filaments and intermediate filaments [Terasawa K, et al. Arch. Histol. Cytol.2006;69:326–340]. The present study aims to determine whether endoskeletal actin filaments contribute to regulate the shape recovery of human erythrocytes. We prepared two types of ghosts: prefixed ghosts which contain endoskeletal network and non-fixed usual ghosts which lack endoskeletal network. To prepare prefixed ghosts, fresh erythrocytes were mildly fixed with 2 % paraformaldehyde and 0.05 % glutaraldehyde in phosphate buffered saline and haemolysed by mild hypotonic Tris buffer with 2 mM Mg-ATP. These prefixed ghosts contained an endoskeletal network which could change their shape quickly by Mg-ATP. In transmission electron microscopy, all the spherical and crenated prefixed ghosts possessed the endoskeletal network as an electron dense matter. Gold particles immuno-labeled for beta actin dispersed over the whole endoskeleton in both crenated and discoid prefixed ghosts. Moreover, cytochalasin B, a blocking agent of fast growing end of long actin polymer, inhibited crenated to discoid shape transition in prefixed ghosts. In non-fixed ghosts, addition of cytochalasin B did not affect recovery to the original shape. Thus, these results suggest that shape transition induced by Mg-ATP is driven through the action of the endoskeletal actin network.

The fishes are the largest group of vertebrates. Two subdivisions can be recognized: the Osteichthyes or bony fishes including about 25,000 species, and the Chondrichthyes or cartilaginous fishes comprising only about 800 species. The latter is separated from the former by several features but the most distinctive is their cartilaginous endoskeleton.

The mammalian erythrocytes had been considered to keep their deformable biconcave shape solely by the membrane and the underlying membranous cytoskeleton. However our previous study showed new aspects that human erythrocytes possessed a cytoplasmic endoskeleton apart from the classical membranous cytoskeleton containing beta-actin and neurofilament heavy chain (NF-H) [Terasawa K, et al. Arch. Histol. Cytol2006; 69: 329–340]. Several studies showed that the intermediate filaments such as neurofilament light chain (NF-L), synemin and vimentin were detected in the nucleated erythrocytes [Granger BL, et al. Science.1983; 221: 553–556] and extended from the nuclear envelope to the membranous marginal bands [Granger BL, et al. J. Cell Biol.1982; 92: 299–312]. In the present study, we asked whether the intermediate filaments such as NF-L and vimentin also exist within the newly found endoskeleton of anucleated erythrocytes. NF-L and vimentin were detected within erythrocytes by western blotting and immunofluorescence. The NF-L were detected along the hillside filament group running parallel to the slope between convex periphery and the concave center and vimentin was distributed along several filaments in the whole erythrocytes by the ion-etching/scanning electron microscopy combined with immunocytochemistry. At the hillside region NF-L co-existed with vimentin along the hillside filaments by back scatter emission signals. We concluded that the endoskeletal filaments of the erythrocyte contain intermediate filaments such as NF-L, NF-H and vimentin as those of the nucleated erythrocytes of avian or lower vertebrates. The intermediate filaments of the endoskeleton within the erythrocytes may keep its unique biconcave disc shape against external circumstances.

Hagfish and lampreys are unusual for modern vertebrates in that they have no jaws and their skeletons are neither calcified nor strengthened by collagen — the cartilaginous elements of their endoskeleton are composed of huge, clumped chondrocytes (cartilage cells). We have discovered that the cartilage in a 370-million-year-old jawless fish, Euphanerops longaevus, was extensively calcified, even though its cellular organization was similar to the non-mineralized type found in lampreys. The calcification of this early lamprey-type cartilage differs from that seen in modern jawed vertebrates, and may represent a parallel evolutionary move towards a mineralized endoskeleton.

The durability and function of three ankle-foot prostheses fabricated using a naturally articulated, fresh cadaveric human bone endoskeleton set in a fiber reinforced rubber shell were studied. Radiographic and force-deflection analyses before and after cyclic dorsiflexion for 5,000, 100,000, and 3 million cycles revealed no structural or functional changes. The endoskeleton foot compared favorably with the Jaipur arikle- foot prosthesis. It is concluded that formalin-fixed fresh foot bones with intact articulations obtained from cadaveric or surgically amputated limbs are suitable for use in ankle-foot prostheses because they withstand prolonged use without func- tional or structural deterioration.

This report describes the construction and evaluation of an ankle-foot prosthesis using human cadaveric bones as the endoskeleton inside a fiber-reinforced vulcanized rubber shell. Cadaveric bones and exhumed skeletal bones were used. Three designs were fabricated, subjected to radiographic evaluation, and underwent 4-week field trials of normal daily use by a unilateral below-knee amputee. The rubber shell retained the position of the bones, permitted movements at the joints in various stages of the stance phase, and restored the bones to their neutral position when the foot was unloaded. The cadaveric prosthesis provided for plantar flexion of the foot when the heel was loaded and for locking of the joints to restrain excessive movement when the foot came to rest. While fresh cadaveric bones withstood all the stresses of active walking, exhumed macerated bones fractured and fragmented with use.

At present the detailed mechanism for transmembrane interactions is not known and a protein linked to the endoskeleton as well as to the exoskeleton has not been described as yet. The H2 complex, a transmembrane protein, consists of heavy and light chains, the latter is named beta-2-microglobulin. In order to look for an association of beta-2-microglobulin with an exoskeleton protein, we examined the extracellular matrix proteins, collagen type I, type IV, fibronectin, amyloid P, the solubilized glomerular basement membrane and lamiriin in respect to their interaction with the light chain. The heavy chain is known to bind strongly to the endoskeleton protein actin. Only laminin and the glomerular basement membrane bound firmly to the beta-2-microglobulin; 3 M urea was necessary to dissociate the formed complex. Incubation with beta-2-microglobulin antibody prevented binding of beta-2-microglobulin to laminin and the glomerular basement membrane on affinity chromatography columns. Antiserum to the glomerular basement membrane in turn prevented binding of beta-2-microglobulin to the glomerular basement membrane, whereas antibodies against the basement membrane collagen type IV failed to inhibit this binding to the glomerular basement membrane. Beta-2-microglobulin also bound to ñbronectin but this complex was dissociated with 1 M urea. In a rosette assay beta-2-microglobulin antibody and antiserum to the glomerular basement membrane reduced attachment of glomerular cells to beads coupled with laminin and solubilized glomerular cells to beads coupled with laminin and solubilized glomerular basement membrane. Also antibody against fibronectin reduced attachment of glomerular cells to fibronectin-coated beads. In an organ reconstruction assay, glomerular cells showed reduced binding to the glomerular scaffold if antibodies to the solubilized glomerular basement membrane or fibronectin were applied, but not if anti-type-IV collagen antibodies were used. This points to the role of laminin and fibronectin for the attachment to glomerular cells, where the receptor could be identified as beta-2-microglobulin, the light chain of the H2 complex, thus linking the endoskeleton with the exoskeleton. Only differences in the binding affinities between laminin and fibronectin were detected.

Kelp bass ( Paralabrax clathratus ) and leopard sharks ( Triakis semifasciata ) are characterized by an acellular (anosteocytic) bony skeleton and a focally calcified cartilaginous endoskeleton, respectively. These skeletal forms are not considered to function as mineral reservoirs. Previous studies showed that implanted bone particles are resorbed in rats by large multinucleated cells with ultrastructural features (ruffled borders) characteristic of osteoclasts. We tested the ability of fish to resorb bone matrix and to adapt to reduced salinity conditions. Bone particles were implanted in sharks and bass maintained in seawater (34 ppt, 40.5 mg of calcium per dl) or in diluted seawater (26 ppt, 28.5 mg of calcium per dl). Sera and elicited tissues were harvested 4 weeks later. In sharks, bone particles were not resorbed, and multinucleated cells were not evident under either normal or hyposalinity conditions. Shark sera were isoosmolar with the seawater or diluted seawater, with serum chemistries of the hyposalinity group reflecting the 23% reduction in environmental minerals and electrolytes, compared to sharks in normal seawater. In marked contrast, bass adapted to diluted seawater resorbed bone particles and maintained normal serum chemistries. Electron microcopy showed that the bone particles were surrounded by large, foamy multinucleated cells, many with membrane specializations typical of osteoclasts from higher vertebrates, i.e., extensive clear zones apposed to intact bone matrix and active ruffled borders overlying areas of matrix undergoing dissolution. Although osteoclasts had not been described in these fish, this study shows that bass have stem cells that can be stimulated to differentiate into bone-resorbing osteoclasts.

Five concentrations of nitrogen mustard (methyl-bis-chlorethylamine) have been administrated to different stages of development of trout embryos (Salmo gairdneri), in order to study their effect on the formation of both pelvic fins soft tissue and skeleton. Sensitivity of epidermis and mesoderm toward this cytotoxic agent has been assessed histologically. Although both components are sensitive to nitrogen mustard, mesoderm is more sensitive than epidermis. These results are compared with the results of similar studies on tetrapod limb buds. The pelvic fin skeleton of some treated animals was doubly stained in toto for cartilage and bone by Alcian blue and alizarin, followed by clearing. Other specimens were processed for histological serial sections. Analysis included comparison of the following parameters: (1) dose of nitrogen mustard, (2) stage of fin bud development at the time of treatment, (3) importance of necrosis in the fin bud, and (4) abnormalities of the endoskeleton of the fin (pelvic girdle and radials) and of the dermal skeleton (lepidotrichia and actinotrichia) one month after the hatching of control animals. Results suggest (1) that material of endoskeleton and lepidotrichia are laid down simultaneously, and (2) that differentiation of actinotrichia is independent of differentiation in endoskeleton and lepidotrichia.

The lecithotrophic development of Ibla quadrivalvis comprises six naupliar stages and a cypris stage. Despite lecithotrophy, the planktonic nauplius has a complete skeletal musculature, associated in part with a ventral endoskeleton. The naupliar musculature remains unchanged for the first five naupliar stages. Modifications of the musculature begin to occur in stage VI, preliminary to the change at the sixth moult to the musculature of the cyprid. In this transition, some naupliar muscles are histolysed, some cypris muscles arise as new developments and some muscles are transformed from naupliar muscles to cypris muscles. Details are given of these changes. The pattern of muscle development during the change from nauplius to cyprid in I. quadrivalvis is compared with the more extreme histolysis and replacement of the musculature during the nauplius-cyprid moult of Semibalanus balanoides . The cypris muscu­lature is also compared with that of the rhizocephalan Lernaeodiscus porcellanae . In spite of lecithotrophy, I. quadrivalvis retains a relatively generalized arrangement of thoracican naupliar muscles and cypris muscles and a generalized transition from one to the other. The evolution of total muscle replacement at the nauplius-cyprid moult in advanced thoracicans is discussed.

The innervation and neuromuscular physiology of the deep flexor muscles in the thorax of the crayfish, Orconectes rusticus are described. Four muscles arise ventrally from the endophragmal shelf and join at segmental inscriptions to form a single functional mass. Deep flexor 1 (DF1) extends from the anterior thoracic endoskeleton to be joined by DF2, DF3, and DF4 in more posterior segments. The mass inserts on the abdominal flexor at the common flexor inscription. Motor axons from thoracic ganglionic third roots 1–3 innervate the deep flexor muscles. Light and electron microscopical examination indicates that the third root of the first thoracic ganglion contains only three or four axons that innervate the musculature, and the third root of the second thoracic ganglion usually contains five. The largest number of deep flexor axons (10) occurs in the third root of the third thoracic ganglion. Methylene blue staining and microelectrode recording methods show that each deep flexor muscle fiber is innervated by three motoneurons: the motor giant, a non-giant excitor and an inhibitor. The motor giant elicits excitatory postsynaptic potentials (EPSPs) that rapidly antifacilitate, while the non-giant excitor elicits EPSPs that do not antifacilitate. Both excitors produce spiking activity in the deep flexors. The inhibitory motor neuron reduces the amplitude and duration of the EPSP and prevents spiking activity. These results show that the thoracic deep flexor system is similar to the homologous system in the abdomen.

The species of four separate phyla,Periloculina, Pseudolacazina, elongateLacazina and compressedLacazina are revised and illustrated. By their common, pillared endoskeleton and miliolid coiling, they represent a common, single Late Cretaceous branch of the Fabulariidae endemic in the Pyrenean faunal province. Alveolinidae are represented in this province only by two unconnected genera,Helenalveolina n. gen. andSubalveolina, the latter closely related to American groups of larger porcelaneous foraminifera. They are interpreted as separate endemic offspring of streptospiral stem miliolids.

The cephalothoracic muscles associated with the foregut and feeding appendages of Armadillidium vulgare (Latreille) are described with a view toward establishment of functional morphologic relationships based on studies of dissections, special endoskeletal preparations, and whole-organism serial sections. The complex endoskeleton of the head resembles that of Ligia oceanica in certain aspects. The maxillipeds flex only weakly, but are capable of strong adduction and anterior-posterior movement. The maxillae are weak appendages, but the complex musculature of the maxillules suggests powerful movements associated with food manipulation. The asymmetric mandibles are triturating appendages moved by adductors and abductors. The labrum is held in place over the mouthparts by muscles that permit only slight mesial movements when the mandibles are opened. Musculature of the esophagus includes circular and longitudinal intrinsic bands and 17 pairs of extrinsic dilators. Coordinated sequential dilation and constriction along the length of the esophageal tube produces peristaltic-like movements. The triturating function of the gastric mill is effected by five pairs of extrinsic muscles. Intrinsic circular muscle constricts the pressing apparatus; two pairs of extrinsic muscles contract simultaneously to dilate the press. The foregut appears to be modified for food handling, transport, storage, trituration, pressing, and straining of food. Several published reports have referred to various and isolated aspects of the cephalothoracic extrinsic muscles and the intrinsic musculature of the isopod gut. In a comprehensive description of the digestive anatomy of Edriophthalme, Ide (1892) noted only briefly foregut musculature, as did Reh6rst (1914). However, Ide observed a pair of extrinsic muscles forming a crosslike pattern, which he called the "Cross of St. Andrew." Jackson (1926) contributed significantly to our knowledge of isopod anatomy by way of a detailed description and discussion of the head endoskeleton and appendage musculature of Ligia oceanica. Nicholls (1931) provided a detailed account of foregut structure and its musculature in L. oceanica, as well as the processes of feeding, digestion, and absorption. Radu (1948) described the intrinsic and extrinsic muscles of the oniscoid esophagus, cardiac stomach, and pyloric stomachs, but he did not discuss their functinal relationships. Manton (1963) effectively complemented Jackson's work, integrating much scattered information to offer comprehensive functional morphologic interpretations of crustacean jaw mechanisms. The functional morphology of the alimentary canal in two carnivorous intertidal isopods, Eurydice pulchra and E. affinis, was treated by Jones (1968) in a comparison of the structural and functional modifications related to the carnivorous mode that characterizes the genus with those of herbivorous and omnivorous isopods. Schmitz and Schultz (1969) reported that the esophageal lumen of Armadillidium vulgare is opened and closed both by intrinsic and extrinsic muscles and contended that the gastric mill is moved in a similar manner to form a closing apparatus. Subsequently, Schultz (1973b) described the foregut musculature of Lirceus garmani, referring briefly to similarities in L. fontinalis (see also Schultz, 1973a). The work of Hassall (1977) detailed the structure, as well as the functional morphology, of the mouthparts and foregut in Philoscia muscorum. The purpose of the present paper is to contribute further to our knowledge of

The postmolt phase of the molt cycle of the blue crab was divided into soft (2–3 h), leathery (2–3 h), and paper shell (4–18 h) stages based on the rigidity of the lateral spine. The intermolt stages were determined by observing the growth of the endoskeleton, and the appearance of the membranous layer, at the edge of the paddle at low power magnification. The intermolt phase was divided into Stage C1 (exocuticle thicker than endocuticle), C2 (endocuticle thicker than exocuticle), and C 3 4 (membranous layer present). The onset of the premolt period was observed to occur before the white line condition. Stage C 3 4 was the dominant phase of the intermolt period and the duration of this stage was highly correlated with the length of the molt cycle. The average molt cycle duration was 38 days.

A new genus and two new species of Dercetidae, Rhynchodercetis gracilis, sp. nov. and Dercetoides venator, gen. and sp. nov., from Lower Cenomanian (Upper Cretaceous) beds of Israel are described. The caudal endoskeletons of these new species are the first of the family Dercetidae to be described in detail. Rhynchodercetis gracilis is distinguished mainly by having the relatively longest upper jaw of all species, the presence of an interoperculum, a relatively long caudal vertebra in advance of the caudal endoskeleton, and a convoluted suture between the second and third hypurals. Dercetoides venator represents a Dercetis-like fish with upper and lower jaws that terminate anteriorly at the same level. It is distinguished, mainly, by an unroofed post-temporal fossa, the presence of an interoperculum, two pairs of transverse processes on each precaudal vertebra, and a convoluted suture between the second and third hypurals. An analysis of phylogenetic relationships in the family Dercetidae suggests...

The anatomy, histology, and post-larval development of the ♂ and ♀ reproductive systems of the sugarbeet root maggot, Tetanops myopacformis (Roder) (Otitidae), are described. The ♂ system consists of the aedeagus, andrium, ejaculatory bulb and apodeme, 3 pairs of accessory glands, paired vasa deferentia, and paired testes. The reproductive system of T. myopaeformis males differs from other described acalypterate ♂ systems as follows: structure of andrial endoskeleton; bootshaped ejaculatory apodeme; 2 pairs of short bulbous accessory glands; and brown coiled testes. Spermatids are first evident 2 days post-pupariation with mature spermatozoa present in newly emerged adults. Most males are capable of mating 1–2 days postemergence. The ♂ reproductive system consists of a pseudo-ovipositor, vagina, bursa copulatrix, ventral receptacle, 3 spermathecae, paired accessory glands, common oviduct, paired lateral oviducts, and paired ovate ovaries. The reproductive system of T. myopaeformis females differs from other described acalypterate female systems as follows: type of sensilla near apex of ovipositor; presence of 2 ventral diverticula of the vagina, the bursa copulatrix and ventral receptacle; and 3 spermathecae present on 2 ducts. Vitellogenesis begins within 9 days post-pupariation and is not complete until 1–2 days postemergence. Most females are sexually mature and capable of oviposition within 2 days postemergence. During copulation the aedeagus coils transversely 1–2 times in the bursa copulatrix. Spermatozoa are transferred in bundles from the testis to the bursa copulatrix. The bundles break up shortly after entering the bursa copulatrix.

1. A histochemical study has been made of alkaline phosphatase in the endoskeleton of dogfish embryos of 18-115 mm. 2. The distribution of phosphatase is compared with that of insoluble calcium salts. 3. Phosphatase was first noted in the chondrocytes and perichondrium at 47 mm. and in the cartilage matrix at 58 mm. 4. Calcification occurred first in the neural plates at 58 mm. and in the skull at 74 mm. No calcification was observed in zones devoid of extracellular phosphatase. 5. As the intensity of calcification increased the amount of phosphatase tended to drop. 6. It is concluded that in elasmobranchs, as in higher animals, extracellular phosphatase is an essential precursor of calcification.

In a former paper, descriptive of the type remains of Polacanthvs Foxii , some account was given of its dermal armour, but the description was unavoidably very incomplete, owing to the extremely fragmentary state of the parts originally composing it. Broken up by its discoverer into pieces small enough for convenient stowage and transport in bags from the cliffs to the village of Brighstone, two-and a-half miles distant, and then uncared for during fifteen years, the great dorsal shield, when after Mr. Fox’s death his collection was acquired by the British Museum, was represented by several hundreds of disconnected pieces, many of these being of less size than one cubic inch. It was also evident that many had been lost. In this mutilated condition the reconstruction of the shield appeared hopeless, but at length, under the guidance of the heads of the Palæontological Department, this has been accomplished by Mr. Hall and Mr. Barlow (“Masons”), who brought to the task a painstaking perseverance and skill worthy of the highest praise. Although now, doubtless, much less complete than when laid bare in the cliff by Mr. Fox, the reconstruction (which has consisted strictly in a faithful reunion of the disconnected scattered fragments) renders very intelligible the discoverer’s first impression, viz., that “he had before him the carapace of a gigantic turtle,” and it confirms his opinion of the position of the shield, viz., that it covered the rump and loins. The dimensions of the shield, given by Mr. Fox in a MS. note, 3 feet 3 inches by 3 feet, were taken roughly in the cliff before the shield was broken up. In its restored condition its breadth is 108 centims. in front, 105 centims. at its middle, and 48 centims. posteriorly, and its length is 90 centims. The relation of the shield to the pelvic bones makes it evident that the carcass was lying on its belly when it sank into the ooze, and that the shield was later crushed down upon the endoskeleton and flattened out.

Some morphological terms and characters of Chironomidae are discussed. The proposed terminology of the head chaetotaxy is more in accordance with that of other Diptera. The term flagellomere is preferred instead of flagellar segment. The morphology and terminology of tentorium, cibarial pump, maxillary palp, ocelli, and thorax including humeral pit are given special attention. Suggested terminology for the male hypopygium is as follows: gonocoxite and gonostylus for the major genital claspers, volsellae (consisting of claspette and endomere) for the appendices, phallapodeme, sternapodeme, and coxapodeme for the endoskeleton and aedeagal lobe for the "Dritte Spange". The term seta is preferred to such terms as hair, bristle, etc. It is suggested that in the larvae the name premandible be retained for the moment. There seems to be strong evidence for applying the term mentum instead of "hypostomial plate", "hypochilum", or "labial plate". The mentum seems to consist of two plates for which the terms ventromentum and dorsomentum are proposed. The "paralabial plates" are parts of the ventromentum and can be termed ventromental plates. A more correct name for the "glossa" seems to be ligula.

I am indebted to the liberality of Professor Edw. Forbes for many valuable specimens of fossil fishes, procured by Capt. Graves from the Lebanon range; and amongst the number, for the subject of the present memoir, one of the most interesting and remarkable ichthyolites ever brought to light by palaeontological research. The cases of the discovery of fishes belonging to the placoid order, in a condition at all approaching to completeness, are exceedingly rare. The destructible nature of the endoskeleton, and the loose attachment of its component members, attest the probability that decomposition would complete its work ere these records could be engrossed in imperishable characters. That this order was nevertheless extensively represented from the earliest fossiliferous period to the present time, is manifest from the frequent occurrence of the palatal tritores, teeth, and defensive fin bones of the Cestracionts, Hybodonts, and Squales; and of the dental apparatus, caudal weapons, and dermal tubercles of the Rays.

(1) A functional and comparative study has been made of the jaw mechanisms of representatives of the major classes of arthropods, covering, where appropriate, the whole endoskeletal systems of the head and the form and function of other mouth parts, hypopharynx, etc. (2) Mandibles are developed embryologically, and presumably phylogenetically also, in one or other of two ways. Type A, in which the biting structures are developed from a proximal endite or gnathobase (Crustacea, Chelicerata), and type B, in which the mandible is developed from a whole limb, the tip of which and not the base is used for gnathal purposes (Onychophora, Myriapoda, Hexapoda). (3) Two types of movement typical of the more primitive ambulatory trunk limbs have been exploited in mandibular evolution. Type I mandibular movement uses the promotor-remotor swing of an ambulatory or swimming coxa on the body, but the axis of swing may be shifted in various ways (Crustacea, Thysanura), and type II mandibular movement uses the prehensile action in the transverse plane of a coxa or coxa and telopodite. Type II is found in Myriapoda, where segmentation of the whole-limb mandible is essential, and direct transverse gnathobasic biting is employed by Limulus. Mandibles of types I and II appear to have evolved independently in the named examples. (4) The more primitive examples of type II mandibles suit fine food feeding and the scratching of food surfaces. The gape is small, biting, if any, is weak, and added hydraulic efficiencies enable fine particles to be sucked up by terrestrial types (Chirocephalus,Hemimysis,Paranaspides,Petrobius). (5) Biting in the transverse plane is not a primitive attribute of the Arthropoda outside the Chelicerata and certain Myriapoda. In the more primitive Crustacea and Hexapoda transverse biting is absent and there is little basic adduction and abduction. Transverse muscles primarily serve promotor-remotor rolling movements. No example has been found of a so-called monocondylic mandible of a crustacean or of a hexapod which exhibits freedom of movement in all directions from this point and a basic power of transverse adduction, whether or not the mandible possesses a formed dorsal articulation. (6) Strong biting in the transverse plane suiting hard or large food is a repeated end term in arthropodan evolution. The examples considered are: some Decapoda, Peracarida, Pterygota, Diplopoda and Symphyla. Adduction in the transverse plane is mechanically simple, but abduction presents great problems, hitherto not appreciated, which have had to be resolved by every group of animals attempting to evolve such mandibles. The resolutions of the difficulty are various, mutually exclusive, and independently evolved by mandibles of all types. (7) The feeding mechanism ofLimulusis described. The jaw mechanisms ofLimulusand of Crustacea are fundamentally different and have probably been evolved in independence. (8) The validity of the evidence for the existence of a pre-coxal segment in Xiphosura needs reconsideration. (9) The rolling whole-limb mandibles ofPetrobiusarenot far removed from a central type which could have given rise to the various mandibles occurring throughout the Hexapoda. It is shown in some detail how this mechanism is parallel to but different from that of the rolling gnathobasic mandibles of the more primitive Crustacea. Differences between the mandibles of Hexapoda and Crustacea concern mandibular form, musculature, movement and derivation; the head endoskeleton, and the form and movements of maxilla 1 are also different. The superficial resemblances are considered to be due to convergence between mandibles of unlike origin which utilize the same type of movement of an ambulatory limb. (10) Present-day animals show how thePetrobius-type of jaw mechanism could have given rise to (i) the strong transverse biting of the Lepismatidae and Pterygota with loss of hydraulic efficiency of the Petrobius type and to (ii) a further development of the rolling movement, together with protrusibility of mandibles, which has been made possible by entognathy in the Apterygota. These two trends are mutually exclusive. (11) Entognathy is a condition permitting great proximal mobility of the mandible and hence confers the powers of mandibular protrusion which are absent in strong closely articulated mandibles. Entognathy in essentially similar form, but differing in details, has been evolved in Onychophora, Chilopoda, Pauropoda, Collembola, Diplura and Protura. The ‘Entognatha’ is not considered to be a valid taxonomic group but one of convergence. (12) A basic pattern of: mandibular structure, musculature, movements, associated head endoskeleton, and of the structure and movements of maxilla 1 is recognizable throughout the less specialized Pterygota, Thysanura, Collembola and Diplura, so linking these groups together by characters having nothing to do with the possession of three pairs of legs. This basic pattern of mandible and maxilla 1 is not found in the Myriapoda. (13) A unified system of skeletal tendons and apodemes exists within the Arthropoda which has hitherto been imperfectly described. Anterior and posterior tentorial apodemes are present throughout the less specialized of the Hexapoda in essentially similar form. The segmental tendon system, present embryologically in all body segments in many animals, occurs in the adult hexapod head except where strong transverse biting has been evolved, and its presence then is consequently not required. Hexapod-like tentorial apodemes are absent in Crustacea, but homologous anterior tentorial apodemes are present in Myriapoda where their mobility is enhanced. Rigidity of tentorial apodemes is found in hexapods where strong transverse biting has been evolved (Pterygota). (14) The details of the feeding mechanism of a chilopod are described. The mandibular mechanism has clearly been derived from the same basic transversely moving mandibles of the type seen in Diplopoda and Symphyla, but modified by the development of entognathy to give a highly specialized mechanism suiting carnivorous feeding and crevice living, and not found in any other group. (15) The Chilopoda, Diplopoda and Symphyla all appear to have obtained direct transverse biting without any preliminary rolling mandible such as seen in Thysanura, but segmentation of their mandibles is essential. All have used the mobility of the anterior tentorial apodemes to provide (Diplopoda) or enhance (Symphyla and Chilopoda) the abductor force which opens the jaws. The differences between the mandibular mechanisms of Chilopoda, Diplopoda and Symphyla indicate independent evolution from a common type and no one of these three classes could readily give rise to the mandibular mechanisms present in either of the other two. The term Myriapoda, indicating affinity between Chilopoda, Diplopoda, Symphyla and Pauropoda deserves to be reinstated. (16) The symphylan mandibular mechanism, together with the structure and use of maxilla 1, the mobility of the anterior tentorial apodeme, and the presence of the myriapodan maxilla 1 salivary gland, are so entirely opposed both to the thysanuran condition and to the directions of evolutionary change seen in the Pterygota and entognathous Apterygota (whose basis appears to lie in the Thysanura) as to make the symphylan theory of insect origin untenable. (17) It is concluded that jaws have evolved independently in (i) the Chelicerata, (ii) the Crustacea and (iii) the Onychophora—Myriapoda—Hexapoda series. Within the latter the jaws in the Onychophora must have evolved very early, before much cephalization had taken place. The mandibular mechanisms of the Myriapoda and Hexapoda are so differ ent as to indicate that there can be no close connexion between these two groups of classes apart from a very distant common origin. The parallel evolution of jaws in arthropods must date from the earliest differentiation of the major classes. The Mandibulata cannot be regarded as a related group, but the term may serve to indicate a Grade of advancement. The bearing of these results on taxonomic systems is discussed.

Summary 1 The endites of the pedipalps form an apparatns for gripping the hair. 2 The pedipalpal endite has powerful adductors but shorter and weaker abductors. 3 Taking the musculature and curvature of the endites into consideration, it seems unlikely that the animal can release the hair. 4 The food appears to be scales and the secretions of epidermal glands scraped off the hair by the chelicerae. 5 The gut has virtually lost the lateral caeca of the more typical Sarcopti-formes, and shows no clearly differentiated post-colon. 6 The female reproductive system has developed a long median glandular common oviduct. 7 The female system shows the bursa copulatrix and receptaculum seminis typical of Tyroglyphoidea. 8 By loss of accessory glands the male reproductive system has come to resemble that of the female quite closely. 9 The posterior region of the suboesophageal ganglion mass is subdivided into a pair of lobes. Each lobe innervates legs III and IV, the genital valves and dorso-ventral muscles of its own side. 10 The muscles associated with movements of the gnathosoma on the podosoma are lost. 11 Development of lateral plates on the tectum of the gnathosoma and extensions of the epimera of leg I to articulate with the pedipalpal coxae render the gnathosoma immobile. 12 The adductor system of the legs is modified in that it has its origins not on the body wall or tendinous endoskeleton but on the epimera in the case of legs I and II and on the posterior end of the sternum or an internal projection of the body wall in the case of legs III and IV respectively.

A brief account and new restorations of the Scottish Middle Old Red Sandstone fish Rham phodopsis are given, based largely on new material from Edderton, Ross-shire. The Edderton material is of the species Rliamphodopsis threiplandi Watson, previously known only from A chanarras, Caithness. The known material of Rhamphodopsis trispinatus Watson, from Moray Firth and Cromarty nodule beds, has been restudied for comparative purposes, and notes are also given on some ptyctodonts from the Upper Devonian of Wildungen, Germany. New points in the structure of Rhamphodopsis concern mainly the sensory line system, jaws, cervical joint, and pelvic fins and associated structures. The occurrence of strong sexual dimorphism in the pelvic region is confirmed, and descriptions are given of the ‘claspers' in males, and of the large scale-bearing pelvic fins and their endoskeleton in females. Some consideration is given to the biology of ptyctodonts.

1. The ichneumonid parasite Gelis corruptor is trimorphic in the development of wings: females are invariably apterous; males may be either macropterous or micropterous. 2. Females show no trace of wing-buds in the pupa and are without wing-disks in the late larval stage. The female apteryis a sex-limited character and is of genetic origin. 3. All male larvae have wing-disks and are potentially fully winged males. On a host providing adequate nourishment, the male larva develops into the macropterous form; on a host providing meagre nourishment, it develops into the micropterous form. Eggs or young larvae transferred from a small to a large host develop into macropterous males; larvae removed from large hosts before they have finished feeding develop into micropterous males. The dimorphism of the male sex is therefore controlled by the host viewed as a quantity of food. 4. The two forms of males differ not only in the development of the wings but also in the structure of the thorax, the size of the ocelli, the form of the endoskeleton, and the development, innervation, and tracheal supply of the thoracic muscles. 5. The trimorphism is strict, since all females are apterous and (with the exception of one abnormal specimen) all the males examined belong without intermediates to either the macropterous or the micropterous form. 6. The principal differences observed between the three forms all appear to be bound up with the condition of the wings. How the development of this complex of characters is organized, particularly in the two forms of males, presents an interesting problem of morphogenesis.

Morphology of adult female and male reproductive systems of Strumeta tryoni (Froggatt) is described and figured. Growth changes in adult male reproductive endoskeleton are described under differing conditions of temperature and light intensity. For the environmental conditions studied, physiological age was correlated with size of the male reproductive endoskeleton and a method for distinguishing teneral from sexually mature adults is given.

The endoskeleton of the kuruma prawn Penaeus japonicus was grossly described with male exuviae. Its morphology was compared to that of crabs. Thestructure of cephalic and thoracic portions of the exuvial endoskeleton had largedifferences in the epistoma as well as the procephalic processes as concerns cephalic sternites, and in the median sternal elements as well as lateral pleuro-sternalarms as concerns thoracic sternites.

The neurocranium, pectoral fin, and teeth of a second specimen of Squatinactis caudispinatus from the Upper Mississippian Bear Gulch Limestone of Montana are described. The cladodont teeth place this chondrichthyan in the order Cladodontida, but the postorbitally elongate braincase is not similar in detail to those of the marine Mississippian Tamiobatis and the predominantly freshwater xenacanthids. The pectoral fin endoskeleton is most parsimoniously derived from one similar to that of Cladoselache, and reinforces the isolated position of Squatinactis.

The Chilopoda possess a bewildering array of muscles and no attempt will be made here to catalogue them. Meinert (1883) described the head muscles of Scolopendra and Bekker (1926, 1949) the trunk muscles of a geophilomorph and a scolopendromorph and compared the dorsal musculature of Cryptops and Lithobius . Bucherl (1940) described the musculature of Scolopendra viridicornis Newport, and Jangi (1966) that of Scolopendra morsitans though the trunk musculature was dealt with only briefly. The extrinsic and intrinsic musculature of the antennae of S. morsitans and the musculature of its terminal legs were described by Jangi (1960, 1961). Applegarth (1952) described the musculature of the head of Pseudolithobius megaloporus (Stuxberg), Rilling (1960, 1968) the head and trunk musculature of Lithobius forficatus in great detail and Fuller (1963 a ) the musculature of Scutigera, Necrophloesphagus and Cryptops . Manton (1965) investigated the musculature of members of all five chilopod orders: she found Bekker's descriptions of the musculature of geophilomorphs and scolopendromorphs accurate but she could not entirely confirm his findings on Cryptops . She confirmed Rilling's (1960) observations on Lithobius . Trunk muscles The arrangement of the trunk musculature in myriapods has been summarised by Manton (1973). She distinguished six groups of trunk muscles: superficial, dorsal, lateral and sternal longitudinals, deep oblique and deep dorso-ventral muscles (Fig. 46).

The tesserate pattern of endoskeletal calcification has been investigated in jaws, gill arches, vertebral arches and fins of the sharks Carcharhinus menisorrah, Triaenodon obesus and Negaprion brevirostris by techniques of light and electron microscopy. Individual tesserae develop peripherally at the boundary between cartilage and perichondrium. An inner zone, the body, is composed of calcified cartilage containing viable chondrocytes separated by basophilic contour lines which have been called Liesegang waves or rings. The outer zone of tesserae, the cap, is composed of calcified tissue which appears to be produced by perichondrial fibroblasts more directly, i.e., without first differentiating as chondroblasts. Furthermore, the cap zone is penetrated by acidophilic Sharpey fibers of collagen. It is suggested that scleroblasts of the cap zone could be classified as osteoblasts. If so, the cap could be considered a thin veneer of bone atop the calcified cartilage of the body of a tessera. By scanning electron microscopy it was observed that outer and inner surfaces of tesserae differ in appearance. Calcospherites and hydroxyapatite crystals similar to those commonly seen on the surface of bone are present on the outer surface of the tessera adjacent to the perichondrium. On the inner surface adjoining hyaline cartilage, however, calcospherites of variable size are the predominant surface feature. Transmission electron microscopy shows calcification in close association with coarse collagen fibrils on the outer side of a tessera, but such fibrils are absent from the cartilaginous matrix along the under side of tesserae. Calcified cartilage as a tissue type in the endoskeleton of sharks is a primitive vertebrate characteristic. Calcification in the tesserate pattern occurring in modern Chondrichthyes may be derived from an ancestral pattern of a continuous bed of calcified cartilage underlying a layer of perichondral bone, as theorized by Orvig (1951); or the tesserate pattern in these fish may itself be primitive.

The calcified cartilage of the dogfish vertebra has been studied by means of an undecalcified hard tissue method, including microradiography and tetracycline labelling, and electron microscopy. The transversely sectioned vertebra shows a centrum and neural and hemal arches. The mineralized area consists of a narrow but continuous band, which touches the perichondrium, and is formed by chondrocytes that participate in the mineralization of the surrounding matrix. The neural arches appear quite different; the upper parts contain an hypertrophied cartilage and, close to it, an inner zone formed by crescent shaped lamellar bone tissue containing osteoblasts and osteocytes. Tetracycline labelling of these two types of hard tissue reveals a globular calcification with calcospherites and Liesegang rings, at the level of the calcified cartilage, and a strong and linear label of the inner border of the osseous tissue. Transmission electron microscopy shows Type I collagen in the crescent shape area and Type II collagen in calcified cartilage area. The presence of osseous tissue in elasmobranch endoskeleton is discussed in relation to the evolution of the gnathostomes skeleton and the endocrinological control of calcium metabolism.

The ultrastructure of the fowl spermatozoon differs in several ways from that of the mammalian spermatozoon, and the probable implications of the findings for the difficult problem of storing fowl semen in vitro are discussed. The acrosome has a simpler structure than in the mammal and does not spread down over the membrane of the head. Greater structural differences occur in the tail region, the middle-piece of which is particularly prone to deteriorate in vitro. The eleven axial (tail) fibres arise from a centriolar complex in the neck region of the spermatozoon; at this level, and more distally in the wall of the distal centriole, they resemble microtubules in cross-section. The nine outer ones show the triplet tubule structure typical of cell centrioles. The complex ‘endoskeleton’ of segmented columns in the neck, and outermost coarse fibres in the middle-piece and principal-piece of the tail, are absent in the fowl. In the distal part of the middle-piece the tail fibres separate; here and in the principal-piece they show the typical doublet structure seen in the tail of mammalian spermatozoa, cilia and flagella. The principal-piece of the fowl spermatozoon is composed solely of a continuous sheath of amorphous material surrounding the eleven axial fibres; the sheath is absent from the distal end of the tail. In contrast with the situation in the mammal, no segmentation of this material is evident and no continuous lateral columns are present in the tail.

Grafting experiments on H. viridis were performed to determine whether the epitheliomuscular cells of the epidermis and the digestive cells of the gastrodermis normally moved independently. In one set of experiments testes were employed as an epidermal marker and the border between algae-laden and algae-depleted digestive cells as a gastrodermal marker. Testes were often observed to move proximally at a faster rate than the border. In another set of experiments composite animals were made from normal and C 14 -labeled animals. Autoradiograms often showed that the epitheliomuscular cells moved proximally faster than the digestive cells. Moreover, in H. pseudoligactis , the epitheliomuscular cells had more mitotic figures per unit area than the digestive cells. This independent movement and growth makes it impossible to imagine the mesoglea as a “cement” holding the two cell layers together. Mesogleas were isolated in order to see if they had properties consistent with their being a substratum for cell movement. They were found to be elastic and tough and to retain the cylindrical shape of the organism even in the absence of cells. A collagen-like protein is present in the mesoglea as shown by the conditions for its extraction, by the behavior of its heat-denatured products on disc electrophoresis, and by the presence of hydroxylysine and hydroxyproline. The role of mesoglea as an endoskeleton in Hydra is discussed.

Two-stage reconstruction using an antibiotic loaded cement spacer is the preferred treatment method of late hip joint infections. Hip spacers maintain stability of the joint and length of the limb during treatment period. However, as the material strength of bone cement (PMMA) is limited, spacer fractures led to serious complications in the past. This study investigated the load capacity of custom made hip spacers, developed at the 'Klinik für Orthopädie und Orthopädische Chirurgie' (Universitätsklinikum des Saarlandes, Homburg / Saar, Germany), and implanted into composite femurs. In a quasi-static test, non-reinforced spacers tolerated hip joint loads of about 3000 N, whereas reinforced spacers with titanium-grade-two endoskeletons doubled this load up to 6000 N. Even for cyclic loading, endoskeleton-including hip spacers tolerated loads of >4500 N with 500,000 load cycles. Thus, an endoskeleton-including spacer should provide a mobile and functional joint through the treatment course. A generated FE-model was used to determine the fracture stresses and allows for further sensitivity analysis.

The calcareous shells of brachiopods offer a wealth of informative characters for taxonomic and phylogenetic investigations. In particular scanning electron microscopy (SEM) has been used for decades to visualise internal structures of the shell. However, to produce informative SEM data, brachiopod shells need to be opened after chemical removal of the soft tissue. This preparation occasionally damages the shell. Additionally, skeletal elements of taxonomic/systematic interest such as calcareous spicules which are loosely embedded in the lophophore and mantle connective tissue become disintegrated during the preparation process. Using a nondestructive micro-computed tomography (μCT) approach, the entire fragile endoskeleton of brachiopods is documented for the first time. New insights on the structure and position of tissue-bound skeletal elements (spicules) are given as add ons to existing descriptions of brachiopod shell anatomy, thereby enhancing the quality and quantity of informative characters needed for both taxonomic and phylogenetic studies. Here, we present five modern, articulated brachiopods (Rectocalathis schemmgregoryi n. gen., n. sp., Eucalathis sp., Gryphus vitreus, Liothyrella neozelanica and Terebratulina retusa) that were X-rayed using a Phoenix Nanotom XS 180 NF. We provide links to download 3D models of these species, and additional five species with spicules can be accessed in the Supplemental Material. In total, 17 brachiopod genera covering all modern articulated subgroups and 2 inarticulated genera were X-rayed for morphological analysis. Rectocalathis schemmgregoryi n. gen., n. sp. is fully described. Micro-CT is an excellent non-destructive tool for investigating calcified structures in the exo- and endoskeletons of brachiopods. With high quality images and interactive 3D models, this study provides a comprehensive description of the profound differences in shell anatomy, facilitates the detection of new delicate morphological characters of the endoskeleton and gives new insights into the body plan of modern brachiopods.

The author describes the large dorsal shield, which has been recently restored and now exhibits the grouping of the keeled and tuberculated fragments, which in their disconnected and scattered condition had formerly been regarded as portions of separate scutes. This unique specimen shows Polacanthus to have possessed a more complete dermal armature than any other Dinosaur yet described.

Background: The fish-tetrapod transition was one of the major events in vertebrate evolution and was enabled by many morphological changes. Although the transformation of paired fish fins into tetrapod limbs has been a major topic of study in recent years, both from paleontological and comparative developmental perspectives, the interest has focused almost exclusively on the distal part of the appendage and in particular the origin of digits. Relatively little attention has been paid to the transformation of the pelvic girdle from a small unipartite structure to a large tripartite weight-bearing structure, allowing tetrapods to rely mostly on their hindlimbs for locomotion. In order to understand how the ischium and the ilium evolved and how the acetabulum was reoriented during this transition, growth series of the Australian lungfish Neoceratodus forsteri and the Mexican axolotl Ambystoma mexicanum were cleared and stained for cartilage and bone and immunostained for skeletal muscles. In order to understand the myological developmental data, hypotheses about the homologies of pelvic muscles in adults of Latimeria, Neoceratodus and Necturus were formulated based on descriptions from the literature of the coelacanth (Latimeria), the Australian Lungfish (Neoceratodus) and a salamander (Necturus). Results: In the axolotl and the lungfish, the chondrification of the pelvic girdle starts at the acetabula and progresses anteriorly in the lungfish and anteriorly and posteriorly in the salamander. The ilium develops by extending dorsally to meet and connect to the sacral rib in the axolotl. Homologous muscles develop in the same order with the hypaxial musculature developing first, followed by the deep, then the superficial pelvic musculature. Conclusions: Development of the pelvic endoskeleton and musculature is very similar in Neoceratodus and Ambystoma. If the acetabulum is seen as being a fixed landmark, the evolution of the ischium only required pubic pre-chondrogenic cells to migrate posteriorly. It is hypothesized that the iliac process or ridge present in most tetrapodomorph fish is the precursor to the tetrapod ilium and that its evolution mimicked its development in modern salamanders.