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The anatomical studies reviewed by Kuroda (1954) have shown that a remarkable amount of morphological variation exists among shearwater species. At one end of the spectrum members of the genus Calonectris are lightly built, with long wings and a weakly developed sternum-features well adapted to effortless gliding flight but poorly adapted to the use of the wings in swimming under water. The weak pelvis and unstreamlined tarsus are also poorly adapted for swimming. At the opposite extreme, members of the genus Puffinus show a progressive trend towards a sturdy build, with short wings, well-developed sternum and pelvis, and streamlined, compressed tarsus. These features are well adapted for swimming under water with wings and feet, but they require a more laborious flapping rather than gliding flight when the bird is in the air.

A modification of the Kocher clamp used for wire closure of the sternum is described. With the clamp applied securely to the individual strands, the wire can be readily twisted; the shorter length of the clamp allows the surgeon a much firmer grip on the wire and saves considerable time during closure.

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IN “The Descent of Man,” p. 19, under the heading of Rudiments, Darwin refers to the long isolated hairs seen in the eyebrows of certain individuals, as representing similar hairs in the superciliary region of the chimpanzee, baboon and certain species of macacus. An analogous phenomenon, with a different significance, found sometimes in the pectoral region in man, seems to be worth notice. I have recently examined two persons, a male aged twenty-eight and a female aged thirty-three years, both with particularly hairless, smooth skins, and each showing, at a critical point in the pectoral region, certain outstanding hairs set closely together, the former three long hairs an inch in length, and the latter two hairs an inch and a half in length. The point of interest lies in the position and direction of these few scattered hairs, which are as noteworthy, in their way, as “erratic blocks” on a level plain. In the female case the two hairs were set just over the middle of the left second costal cartilage, and they pointed persistently upwards towards the neck. In the male case the three long hairs were set close to the sternum in the left second intercostal space pointing persistently downwards. The situations of these two curious islets of hair are exactly above, on the one hand, and below, on the other, the level at which the upward chest-stream and the downward chest-stream always divide in a hairy subject. The remarkable persistence in their ancestral direction of these few “fossil” hairs, as they might be called, seems to confirm the view that if man has inherited his hairy covering from a simian ancestry it has been modified in many regions by use and habit since he inherited it. We say that a little straw shows the way in which the wind blows, and I submit that sundry stray hairs on the body of man similarly testify as to the trend of certain mechanical forces which have acted and still act upon him.

For the loan of the material which made this study possible I am deeply indebted to Prof. N. Banks of the Museum of Comparative Zoology at Harvard University, to Dr. C. E. Palm and Dr. H. Dietrich of Cornell University, and to Dr. A. B. Gurney of the United States National Museum. Their kindly cooperation and the wealth of help and advice received from Dr. C. P. Alexander and Dr. G. C. Crampton of this department have made this project both interesting and profitable. Isogenus was erected as a genus by Newman in 1833. In 1904 Klapalek split off the subgenus Dictyogenus on the basis of an apical network of crossveins of the wings. In 1912 he erected Isogenoides as a subgenus of Isogenus to receive some North American species with a "nail" on the posterior ventral margin of the seventh abdominal segment of the male. A reanalysis of these groups shows that Dictyogenus, like other Perlodid genera based on very superficial and highly variable wing venational characters, is not valid. The few individuals at hand show, as would be expected in the Perlodidae, that the number and position of apical crossveins varies to such a great extent that intermediates are numerous and the character cannot be used to define Dictyogenus. In addition, thoracic sclerites, mouthparts, and other head structures of Dictyogenus and Isogenus are identical and the genitalia also are of a single type. Isogenoides, however, exhibits some very fundamental differences. In the thoracic sternum of this group are generic characters which are even more distinct and unique than those found bv Klapalek in the genitalia. On the basis of these discoveries I am here synonymizing Dictyogenus under Isogenus; and to give Isogenoides its justified equal standing with related groups I am raising it to generic rank. Isogenus seems to be represented in North America by numerous species, placed in the literature in the genus Perla. Of Isogenoides there are a half dozen North American species known to me. Not a single one of these species, however, has been placed in its proper genus since the original work of Klapalek (1912). Needham and Claassen in their monograph placed them in Isogenus; Banks placed some in Perla; and Frison placed one in Hydroperla. More species of Isogenoides than are discussed here may eventually be recognized as already described and improperly placed in other genera of Plecoptera.

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The structure of the conducting system in the heart of marsupials has been described in some detail (Blair, Davies, and Francis, 1942). The general cardiac anatomy of the native American opossum was reported by Wade and Neely (1949). Nardone and Wilber (1952) described the electrocardiographic changes that take place in the opossum exposed to low temperatures. They do not, however, give an adequately detailed description of the normal values. No information other than this is contained in the ordinarily available literature concerning the functional aspects of the opossum heart (Lepeschkin, 1951; Prosser, 1950; Hartman, 1952). The present paper reports the results of electrocardiographic studies on the opossum, Didelphis marsupialis , and includes data concerning the effects of decamethonium on the heart. Ten animals were involved in these experiments. All, except one, were lightly anesthetized with nembutal before use. One was unanesthetized to ascertain the effect, if any, of the nembutal on the electrocardiogram. Needle electrodes were inserted into the limb muscles. The V lead electrode was inserted into the muscles just to the left of the sternum and …

In his description of congenital conditions of the heart, Osier 1 mentions and defines ectopia cordis as a condition associated with fission of the chest wall and of the abdomen, in which the heart is displaced so that it passes out of the thorax and lies either on the outer surface of the body or in the abdominal cavity. He cites Ellis 2 as following Ranchfuss, who divides the cases into: ( a ) pectoral heart, with fissure of the sternum; ( b ) abdominal heart, in which the organ protrudes into the abdomen through a defect in the diaphragm with or without external tumor, and ( c ) cervical heart. Pfaundler and Schlossman 3 state that ectopia of the heart is more of anatomic than of clinical importance. With ectopia the sternum is wholly or partially absent and the skin may be normal or may also be lacking. Ectopia may be an isolated arrest of

Cytonyssus troglodyti sp. n. is described from the nasal passages of the Carolina wren, Thryothorus ludovicianus, from Louisiana. Although similar to both Cytonyssus andrei and C. temenuchi, the new species differs in the structure of the chelicera, the shape of the dorsal punctate areas, the chaetotaxy and solenidiotaxy of the legs, and the shape of the idiosoma. This is the first report of this genus from the Troglodytidae and from North America. Examination of the nasal passages of a specimen of the Carolina wren, Thryothorus ludovicianus, revealed the presence of mites of the genus Cytonyssus. These differ from other species of the genus and they are described herein as a new species. In the following description all measurements are in microns. The range of measurements of the paratypes and their means follow the values for the holotype in parentheses. Drawings were made with the aid of a camera lucida. Cytonyssus troglodyti sp. n. (Figs. 1-6) Description (based on the holotype 9 and 3 9 paratypes): Acarina; Sarcoptiformes; Cytoditidae Oudemans, 1908; Cytonyssus Fain, 1960. Female: Body small, white in color, angulate anteriorly, rounded posteriorly. Length of idiosoma (gnathosoma included) 350 (320 to 360, 345). Maximum width of idiosoma 280 (250 to 285, 270). Dorsum: A triangular punctate area on the propodosoma, a large rectangular punctate zone on the middle opisthosoma, two lateral punctate areas adjacent to this, and ventrally a small punctate zone connected or not to the rectangular punctate zone on the posterior margin of the opisthosoma. Two pairs of setae located on the anterior triangular punctate zone, 4 pairs on the lateral punctate zones. Venter: Several punctate zones present, mostly in the intercoxal fields. Epimera I very short, fused to form a well-developed sternum. Epimera II, III, and IV free. Anus ventral in posterior region of body. Genital vent longitudinal, located between epimera III and IV, apodemes not distinct. Bursa copulatrix short, indistinct, copulatory orifice posterior to anus on posterior margin of venter. Gnathosoma: Small, with structure as illustrated (Fig. 2). Chelicera very small, indistinct in most specimens, terminating in a Received for publication 14 September 1971. fork-shaped structure with three unequal points. Legs: Length of legs I, II, III, and IV 120 (117 to 120, 118), 116 (112 to 116, 114), 117 (113 to 117, 115), and 125 (120 to 128, 124), respectively. Tarsi I to IV with pedunculate ambulacra. Tarsus I with 6 large transparent curved spines located apically and 4 very fine setae on the dorsal and ventral aspects. Tarsi II, III, and IV each with 6 large curved spines located apically and 3 smaller spinose setae. Tibiae I to III with 1 short spine e ch. Tibia IV with 2 short spines. Genu I with 2 short spines. Genus II and III with 1 short spine each. Genu IV, femurs, and trochanters devoid of setae. Tarsus I with 1 large and 1 smaller solenidion measuring 6 to 8 and 4, respectively. Tarsus II and tibiae I, II, and III each bear apically on the dorsal surface 1 very large solenidion measuring 15 to 17, 16 to 18, 12 to 14, and 10 to 13, respectively. Solenidions on tibiae I and II with slightly swollen bases. Two very small solenidions on dorsal surface of genu I and a single solenidion on genu II. Remaining leg segments devoid of solenidions. Male, nymphs, larvae: Unknown. Host: Thryothorus ludovicianus, the Carolina

Nursery web spiders (Pisauridae) have as their closest known relatives the wolf spiders of the family Lycosidae (Bishop, 1924). Among the differences used to separate these two taxa are the conformation of the egg sac and the manner in which the female spider carries the sac. The pisaurid egg mass is enclosed in a continuous covering of silk and is held beneath the female's sternum by the chelicerae. The lycosid egg sac is composed of two valves. It is attached with webbing and swung below the mother's spinnerets. Gertsch (1949) mentioned that the sternal egg sac position is more ancient and awkward than the abdominal position. The purpose of this paper is to suggest a reason for the maintenance of the sternal egg sac position by pisaurid spiders. McAlister (1959) pointed out that the ability to dive beneath the water is an escape mechanism important to the survival of Dolomedes triton sexpunctatus Hentz. This is probably true for the other species of diving pisaurids. It can be explained that if the ability to dive successfully is an asset to these spiders, then the sternal egg sac position is also advantageous, for it facilitates the diving process more than would the abdominal position. An adult female D. t. sexpunctatus weighing 1.50 gm. (equivalent to 1470 dynes) displaced 1.53 gm (1499 dynes) of water when completely immersed. When this individual is submerged there is a buoyant force of 1499 dynes tending to push her to the surface. The spider must therefore exert a force of 29 dynes upon some support to remain

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Head 0·83 mm. long, shiny orange-yellow, with the clypeus and the adjoining portion of the frons shiny black. Eyes black, prominent, extending laterally beyond the anterior lateral margins of the pronotum. Rostrum brownish black, extending to, but not surpassing, the posterior coxae; lengths of the joints: first 0·53 mm., second 0·76 mm., third 0·4 mm., and fourth 0·6 mm. Antennae brownish black, the third and fourth joints somewhat paler; first joint slightly incrassated, length 0·83 mm., second 2·0 mm., third 1·83 mm., fourth 1 mm. Pronotum shiny orange-yellow, posteriorly somewhat suffered with dark brown; length in middle 1·4 mm., breadth at anterior margin 0·8 mm., at posterior margin 2·0 mm.; sides straight, posterior margin moderately convex. Scutellum shiny black, finely rugosely punctate and regularly covered with pale depressed hairs; length in the middle 1·3 mm. Corium and cuneus similar in colour and pilosity to the scutellum; membrane dark smoky brown, veins shiny black, passing the apex of the abdomen. Sternum: mesostethium and metastethium black, the metastethial orifices and the surrounding areas very pale yellow: undersides of abdomen shiny black, covered with very fine pale hairs. Legs: coaxae blackish brown; femora dirty orange-yellow, suffused at base and apex with brown; tibiae dark brown, armed with fine black spines; tarsi black, strongly pilose.

I HAVE just found that the omosternum of Notidanus, described by me in a recent number of NATURE (vol. xliii. p. 142), was originally described by my friend Prof. W. A. Haswell, of Sydney, who, in his paper “Studies on the Elasmobranch Skeleton” (Proc. Linn. Soc. N.S.W., vol. ix., 1884), has the following passage:—

Case 1.—A colored man, aged 32, single, steward on a merchant vessel, came to the out-patient department of the House of Relief in August, 1906, complaining of "indigestion" for which he had been treated about eight months without benefit. His family and previous personal history were entirely negative, and may be so assumed, without further detailing. His habits with regard to alcohol and tobacco were moderately good. He did not abuse either. His immediate complaint, which was the same as he had been making for eight months, was of "pain in the stomach." Apart from this and the fact that the pain was not clearly connected with the ingestion of food (either aggravated or ameliorated by it) it was impossible to obtain a history which one could fairly say was not influenced by the questions. In other words, the patient's intelligence was such that his volunteered statements were few and

IN 1937, Sachs and Lewis 1 said that ". . . Nevus syringadenomatosus papilliferus . . . appears to be a rare dermatosis when judged by the few cases reported in the United States." They reported 5 cases and could find only 1 case previously reported in the United States. Ormsby and Montgomery, 2 as late as 1948, did not mention additional American cases and used the illustration from Stokes's original report of the first case. Sutton and Sutton 3 cited a case reported by Elliott, of a unilateral nevus on a boy's back, and exhibited a photograph of a case of Ronchese's. This last-mentioned case was of a tumor on the sternum of a woman. This tumor had also undergone squamous cell malignant change, and Ronchese kindly lent his slides of this case to me for study. Incidentally, both Elliott's and Stokes's cases were mentioned in 1921 by Ormsby 4 in his discussion of

On October 19, 1938, we received a Ruffed Grouse (Bonasa umbellus sabini) shot near Duncan that had both legs heavily infected with the mite Cnemidocoptes mutans. The general appearance of the legs was that characteristic of this malady in the domestic fowl. The scales were elevated by the accumulation of granular material under them and there was some hypertrophy of the dermal and epidermal tissue at the base of the toes. Later in the month of October three more birds with this infection from the same locality and one from Clinton, B. C., forwarded by K. Racey of Vancouver, were received. In two of these birds, hypertrophy of the epidermal tissue of the tarsi and feet had proceeded to such a degree that the tarsi were three or four times normal size and in one instance ulceration had commenced. The most advanced case I have examined was a bird shot at Duncan on October 30, 1938. In this individual the entire unfeathered portion of both legs and feet were involved and the scales and claws had been sloughed along with the terminal phalanges on the two third digits. Hypertrophy of the tissue of the feet had rendered these members utterly u eless either for scratching or for perching, ven walking must have been difficult, if not impossible. In this case, also, an area about an inch in diameter on the breast over the keel of the sternum was infected with the same mite. This bird was extremely emaciated and could not have survived more than a few days. In August, 1939, a California Quail (Lophortyx c. californica) was found in a dying condition near Victoria and brought to the laboratory. This bird's legs were infected with Cnemidocoptes and presented an almost identical picture to those of the most severe cases encountered in the Ruffed Grouse.

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