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Populations of three coexisting intertidal gastropods, Nerita atramentosa Reeve, Bembicium nanum (Lamarck) and Cellana tramoserica (Sowerby), were sampled from a shore in Botany Bay, New South Wales, from July 1972 to September 1973. The recruitment and growth rates of each species were analysed from size frequency distributions. Mortality of each age cohort, and longevity, were estimated from analyses of the densities of Nerita atramentosa and Bembicium nanum . Nerita atramentosa showed no significant mortality during the first two years on the shore, but high mortality (at an instantaneous rate of 0.084 deaths/individual/month) after reaching the age of reproductive maturity, which was 20 months from settlement and at a mean shell-length of 13.5 mm. No growth could be detected after reproductive maturity was reached. Longevity of N. atramentosa was estimated as 3–5.5 years. Bembicium nanum juveniles showed higher mortality (at an instantaneous rate of 0.233 deaths/individual/month) than reproductively mature animals (0.060 deaths/individual/month). Reproductive maturity was reached at a mean shell-breadth of 11.0mm, i . e ., about ten months after settlement on the shore. Longevity was estimated as from 4–8 years. Cellana tramoserica showed different growth patterns depending on the time of settlement. The three species showed different patterns of growth and life history relating to variable recruitment (which was demonstrated in all three species) and different rates of mortality of age cohorts.

The densities of populations of Nerita atramentosa Reeve, Austrocochlea constricta Lamarck, Bembiciuin nanum (Lamarck), and Cellana tramoserica (Sowerby) were recorded in 0.25 m2 quadrats on landward and seaward halves of a sheltered and a moderately exposed rock platform from June 1972 to June 1973. The data have been subjected to variance and multiple regression analysis. Differences between densities of each species on the two shores and in the two areas of each shore are discussed with respect to the regressions on littoral height. Densities of Nerita on the sheltered shore, Austrocochlea and Bembicium on both shores, and Cellana, on the exposed shore, increased with height. The density of Cellana on the sheltered shore decreased as height increased. The density differences in the landward and seaward areas on the two shores were attributable to the effect of height for Nerita and Austrocochlea. Height was the major variable affecting the density of these two species on the sheltered shore. Bembicium and Cellana densities on both shores, and Austrocochlea density on the exposed shore, are not primarily determined by height. On the sheltered shore, Nerita and Cellana increased in density with increasing cover of water in rock pools. On the exposed shore, Bembicium and Cellana became sparser with increasing water cover. Bembicium on both shores increased in density with increasing cover of the alga Peyssonelia, as did Cellana on the exposed shore. Cellana and Austrocochlea tended to increase in density with Nerita on the sheltered shore. Cellana tended to be sparse where Bembicium was dense on the exposed shore. The biological effects of substrata and other species on the densities of each species remain unexplained. Significant time effects were found for variations in the densities of Nerita and Cellana on the sheltered shore and of Austrocochlea and Cellana on the exposed shore. The seasonal change in density of Nerita was parabolic with a minimum in summer, and is consistent with the known period of recruitment of this species. The lack of significant time effects on density of Austrocochlea on the sheltered shore is consistent with the known continuous recruitment of this species. The declining density of Austrocochlea on the moderately exposed shore was found, by size-frequency analysis, to be due to reduced recruitment compared with surrounding shores. The density of Cellana on both shores showed seasonal changes, with a maximum in summer, which is consistent with the known period of recruitment in Cellana. The lack of seasonal changes in density of Bembicium is briefly discussed. This type of multifactor analysis identifies biological interactions affecting variation in density of these species. It also corroborates the results of other ecological investigations and determines the relative importance of a variety of physical and biological factors in the distribution of density of intertidal gastropods.

This widely-spread, and, on the whole, well-marked species, has been in so many cases, as it appears to me, confounded with Alaria bispinosa, that it would be a task of no small difficulty to trace out the mistakes that have arisen in consequence. The imperfect figures of Phillips have, no doubt, been the principal cause of thus confounding the two species. Deslongchamps queried the identification, but yet was inclined to adopt it. Morris and Lycett seem to have had no doubt on the subject. “Having had the advantage of examining a large number of specimens, comprising every variety both in form and stage of growth, we feel no hesitation in uniting the two species here indicated.” It is extremely probable that the Great Oolite specimens of Alaria trifida present varietal differences from the Oxfordian types, and they may also in some cases have assumed forms having only one lateral digitation; but higher up in the Jurassic rocks they seem to be very fairly separable for such a genus as Alaria, which is so prone to effect changes in its shell. Such was doubtless the opinion of Morris, who quotes Al. bispinosa from the Lower Calc. Grit and Kel. Rock, whilst Al. trifida is quoted as a distinct species from the Oxford Clay and Kel. Rock of Yorkshire, the Great Oolite form being referred to a variety.

Population energy budgets estimated on the assumption of steady state conditions for Nerita tessellataGmelin, N. versicolorGmelin, and N. peloronta L. on Barbados, W. Indies, are presented. Large differences in population structure, and hence energetics, occurred at different localities along the beach. Relatively high proportions (81 to 88%) of the assimilated energy were lost via metabolism. Assimilation efficiencies ranged from 39 to 43%, net growth efficiencies from 5 to 13%, and ecological efficiencies from 3 to 7%. For each species, production (P), energy flow (A) and total energy consumption (C) were expressed as functions of animal size, in order to facilitate gross estimations of the energy components for other populations for which data on size-frequency and density are available. Respiration studies of all three species in the laboratory failed to detect differences between respiration rates in air or under seawater.

The complex reproductive systems of the mangrove-dwelling Nerita birmanica are described and related to those of other neritids. Gonad condition in both sexes and numbers of spermatophores in males and females varied slightly during a one-year survey. It is concluded that a slight tendency for larger number of “full” ovaries with big oocytes to occur in collections taken shortly before full and new moon does not represent a significant lunar cycle of gonad activity since almost all gonads bore gametes in all stages of development at all times of year. It appears merely that ovulation may be held up during relatively rainless periods after which substantial rain is followed by reduced ovaries lacking large oocytes. In brief, breeding appears to be continous with but slight variation which does not consistently follow observable environmental factors.

The little capsules in which snails of this family deposit eggs are so durable as sometimes to be found adherent to museum specimens; hitherto, however, detailed descriptions of such capsules have been restricted to the capsules long known as made by Neritina fluviatilis in fresh waters of Europe. The present paper adds descriptions, with measurements and sketches, of Neritina reclivata from Florida, Neritina virginea, Neritina punctulata, Theodoxus mneleagris, Nerita peloronta, Nerita alticola, Nerita tesselata and Neritilia succinea from Jamaica, British West Indies. These capsules are found to be remarkable in that the digestive tract aids in their formation; that is, the capsules are made as secretions of the lower oviduct to which mineral particles are added, and these mineral particles are supplied from the intestine and stored up in a special sac opening into the oviduct. Moreover, the mineral particles are of twofold origin; in some Neritinas they come from the ooze taken in with the food and passed through the intestine; in some Neritas they come from the liver as calcospherites, to be passed through the intestine. It is hoped that the data given will aid future descriptions of capsules from other species till a firm foundation is built for utilization of these capsules as aids in taxonomy.

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The shell selection behaviour of Coenobita scaevola Forskal has been examined in a natural population by statistical methods and by selection experiments using shells whose weights had been artificially changed. In a natural population of C. scaevola there was a definite weight index (weightof the shell/weight of the animal) for the shells of each species of snail. The weight index for one population ranged between 0.7 and 13.0, with a maximum (46% of all values) between 1.3 and 1.9. The volume index (volume of the shell/weight of the animal) ranged from 0.7 to 4.0. The maximum (59%) for the shells of all snail species lay between 1.0–1.3. Small specimens of C. scaevola tolerate greater differences in the weight and volume indexes of their host shells than large specimens. A comparison between weight index and volume index shows that shell selection depends on volume. This is probably also true for a small hermit crab, Clibanarius signatus Heller, of the tidal zone. Selection experiments on the weight index showed maximum value for Galeodes of about 1, for Turbo at about 2, and for Nerita between 2 and 4. Selection experiments on the volume index showed that, independent of the species of the occupied snail shell, there was a maximum between 1.0 and 1.5. In selection experiments between shells of different snail species but of equal volumes the selection was made in regard to their weight indexes. At a weight index lower than 1.0 only Natica was preferred, between indexes 1.0 and 1.5 Natica and Galeodes were similar, while at a weight index of 2.0 or more Turbo was chosen. The shells of those snail species which are generally used by Coenobita scaevola are found in the same frequency in the snail fauna of a place as they are occupied by C. scaevola. With the exception of a few species of aquatic hermit crabs which are characterized by flat thoraxes and which live in shells with a long and narrow opening, all other water and land hermit crabs seem to have no relation to the shells of a given snail species. C. scaevola e.g., lives in the shells of 29 snail species. Broken shells or shells with a fouling of calcareous algae are better tolerated by water hermit crabs than by land hermit crabs. Land hermit crabs also live in fossil and subfossil shells.

Nerita undata, N. plicata, N. polita, N. albicilla and N. textilis are common intertidal gastropods on Aldabra Atoll. Each species prefers a different level on the shore and/or different degrees of exposure to wave action. Patterns of zonation, population size-frequency structure and biomass are given. N. undata exhibits 2 distinct ecophenotypes. Normal types occur on expsed to moderately sheltered shores but are replaced by ‘type B’ in extremely sheltered conditions. Differences in shell morphology and population structure are also noted. Foraging by all species was confined to hours of darkness, generally at low tide. Activity of N. polita was induced slightly on overcast days. N. undata and N. textilis are cryptically coloured and often visible during the day. N. plicata is conspicuous, but is protected by a strong shell. N. polita and N. albicilla are often brightly and variably coloured, but both are concealed during daylight. No Nerita were found infected with trematodes, suggesting that the degree of infection was extremely low. Habitats of the Aldabran Nerita are compared with 3 species on Barbados, West Indies.

The reduced right half of the pallial complex of Nerita tessellata, N. fulgurans, N. versicolor, N. peloronta and Neritina virginea comprises a hypobranchial gland, a vestigial gill and the opening of a duct which bears the same relationship to this gill as that of the left kidney to the functional gill. The duct leads from the region of the genital duct corresponding to the renal section of mesogastropods. The posterior part of the glandular genital duct lies in the visceral mass; its relationships are identical with those of the left kidney. The anterior part develops alongside the rectum within the anterior pallial vein. The left half of the pallial complex of Nerita includes a hypobranchial gland absent in Neritina and Theodoxus. The floor of the mantle cavity of Nerita forms an accessory respiratory surface, receiving blood from the anterior aorta. Its blood spaces communicate with the haemocoel and the parabranchial vein. This vein, also present in Neritina and Theodoxus, drains the mantle skirt. In Nerita its importance increases when the snail is out of water and the mantle cavity is used as a lung. The buccal mass of Nerita fulgurans has the same basic organization as that of Monodonta lineata: differences are related to specializations in the neritid radula requiring greater versatility of movement during feeding. It is protruded by lateral and ventral protractor and buccal depressor muscles originating on the body wall and inserted on the posterior radular cartilages. The horns of the anterior cartilages are orientated to the feeding ground by an array of levator muscles unparalleled in the trochid, and by the buccal fold which also spreads the radula and ensures its maximal sweep. The radular membrane is pulled outward by protractor muscles originating on the posterior cartilages and associated with a cartilage in the posterior wall of the sublingual pouch. Food is gathered on the back stroke of the radula which is drawn into the buccal cavity by a powerful retractor muscle associated with a radular diverticulum. The diverticulum is absent in trochids which have muscles for direct retraction of the buccal mass. The absence of salivary glands in neritaceans may be related to the development of the buccal fold; glandular buccal pouches and sublingual glands may compensate for their loss. The oesophageal glands extend through the anterior oesophagus to the buccal cavity; owing to their separation from the mid-oesophagus they are unaffected by torsion. The stomach is a voluminous sac, simplified in that the caecum is lost or vestigial and that the major typhosole ends at the junction of the style sac with the proximal region. The gastric shield forms a tooth, very prominent in Neritina, which can protect the openings of the oesophagus and ducts of the digestive gland.

Nerita albicilla [spec. nov.] N. testa striata, labiis subdentatis: interiore tuberculato. Rumph. mus. t. 22. f. 8. Habitat ad Hitoe., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 778, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita albume [spec. nov.] N. testa umbilicata convexa, umbilico subcordato: lobo explanato. List. conch. 4. s. 5. c. 3. f. 1, 2. Rumph. mus. t. 22. f. B. Vitellus compressus. Gvalt. test. t. 67. f. A, B. Argenv. conch. t. 10. f. T. Kratzenst. Regenf. 20. t. 5. f. 54. Habitat in O. Asiae., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 776, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita vitellus [spec. nov.] N. testa umbilicata subglobosa, umbilico perforato aequali. Rumph. mus. t. 22. f. D. Valvata 5. Habitat in O. Asiae., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 776, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita lacustris [spec. nov.] N. testa laeviuscula cornea, apice exquisito, labiis edentulis. Habitat in Europae lacubus. Testa similis N. littorali, sed cornea, nec vertice carioso. * * * Imperforatae labio dentato., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 778, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

The purpose of the following brief notice is to put on record some observations made in the island of Skye in August 1850, by which the true geological horizon of the so-called “Wealden” of Loch Staffin was determined, and the Oxford Clay added to the series of oolitic strata in the Hebrides. Sir Roderick Murchison, in his “Supplementary Remarks on the Strata of the Oolitic Series and the Rocks associated with them in the Counties of Sutherland and Ross, and in the Hebrides,” read before the Geological Society in November 1827, states that “in the low and ruinous cliff of blue shale, associated with zeolitic and amygdaloidal trap on the north-eastern shores of Loch Staffin, were found, during my late excursion with Professor Sedgwick, flattened masses of shelly limestone containing five species of Cyclas ) one Paludina , one Neritina , one Ostrea , one Mytilus , and some undescribed bivalves,” and remarks that “it adds materially to the interest of these remains, that two species of the Cyclas , the Paludina , and the Ostrea prove to be identical with the fossils of one of the upper beds of the Weald clay described by Dr. Fitton as occurring in Swanage Bay, Dorsetshire, and in the Isle of Wight.” Of these fossils a list is appended to the paper, drawn up by Mr. Sowerby; and besides the references to Weald Clay species, one Cyclas is considered identical with a Barton Cliff shell, and the Nerita is compared with a Woolwich species. When the Duke of Argyll announced

Nerita plicata [spec. nov.] N. testa sulcata, labiis dentatis: interiore rotundato; exteriore utrinque dentibus acutis conicis. M. L. U. Habitat.., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 779, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita peloronta [spec. nov.] N. testa striata, labiis dentatis: interiore planiusculo rugoso. Rumph. mus. t. 22. f. K. Valvata 2 fasciata. Habitat in O. Asiae ad Bandam., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 778, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita polita [spec. nov.] N. testa laevi, labiis utrisque dentatis. Rumph. mus. t. 22. f. I, 2. Valvata alpina. Gvalt. test. t. 66. f. C. Argenv. conch. t. 10. f. K. Kratzenst. Regenf. 16. t. 4. f. 43. Habitat in O. Asiae., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 778, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita fluviatilis [spec. nov.] N. testa rugosa, labiis edentulis. Fn. svec. 1318. List. angl. 136. t. 2. f. 20. conch. 2. p. 1. t. 38. Pet. mus. 67. n. 718. Habitat in Europae cataractis., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 777, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita virginea [spec. nov.] N. testa laevi ovata, labio interiore gibbo denticulato. Bonan. recr. 3. t. 204. Pet. gaz. t. 11. f. 3. Habitat in M. Mediterraneo., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 778, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita histrio [spec. nov.] N. testa sulcata transverseque striata, labio interiore dentato. Rumph. mus. t. 22. f. 6. Habitat.., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 778, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita grossa [spec. nov.] N. testa sulcata, labiis dentatis: interiore convexo rugoso. Rumph. mus. t. 22. f. N. Gvalt. test. t. 66. f. V. Habitat in O. Asiae., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 779, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita bidens [spec. nov.] N. testa laevi, labio interiore bidentato. M. L. U. Habitat.., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 778, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita radula [spec. nov.] N. testa sulcata tuberculis aequalibus, labiis edentulis. M. L. U. Habitat.., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 777, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita mammilla [spec. nov.] N. testa umbilicata ovata glabra, umbilico obtecto, apertura ovata. Column. aqv. t. 52. f. ult. Cochlea nivea. List. conch. 4. s. 5. c. 3. t. 1. f. 3, 4. Rumph. mus. t. 22. f. E. Valvata 7: Albula. Gvalt. test. t. 67. f. C, D. Argenv. conch. t. 10. f. X. Uber tenue. Habitat ad Barbados. * * Imperforatae labio edentulo., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on pages 776-777, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita nodosa [spec. nov.] N. testa nodosa pluribus ordinibus solida, labro angulato. Bonan. recr. 3. t. 173, 174. List. conch. t. 804. f. 13. Gvalt. test. t. 66. f. BB. Klein. ostr. 17. t. 1. f. 30. Habitat.. Affinis Murici Nodo tota structura, sed postice lacuna destituta, qua neglecta ruerent genera., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 777, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita exuvia [spec. nov.] N. testa sulcata, labiis dentatis: interiore tuberculato. Bonan. recr. 3. t. 220. List. conch. 4. s. 1. c. 1. t. 2. f. 5. Rumph. mus. t. 22. f. M. Pet. gaz t. 100. f. 6. Gvalt. test. t. 66. f. CC. Argenv. conch. t. 10. f. I. Habitat in O. Americae & Asiae., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 779, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita glaucina [spec. nov.] N. testa umbilicata laevi, spira obtusiuscula, umbilico semiclauso: lobo gibbo dicolore. List. conch. 4. s. 5. c. 1. t. 5. f. 1. Rumph. mus. t. 22. f. A. Valvata laevis. Gvalt. test. t. 67. f. M, P, T. Habitat in O. Europaeo., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 776, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita littoralis [spec. nov.] N. testa laevi, vertice carioso, labris edentulis. List. angl. 164. t. 2. f. 3. conch. t. 4. s. 8. f. 39. Pet. mus. 67. n. 717. Habitat ad Maris Europaei littora scopulosque, modis innumeris variegata., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 777, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita viridis [spec. nov.] N. testa laevi viridi, labio interiore medio crenulato. Brown. jam. 399. N. minima viridis. Habitat ad Minorcam, Jamaicam. E. Brander. Testa parva admodum, viridis, interdum fusco lacteoque undata, ad labium albo-maculata., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 778, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita canrena [spec. nov.] N. testa umbilicata laevi, spira submucronata, umbilico gibbo bifido. Rumph. mus. t. 22. f. C. Valvata 4. Gvalt. test. t. 67. f. E, Q, R, S, V, X. Argenv. conch t. 10. f. C. Kratzenst. Regenf. 10. t. 3. f. 34. Habitat in O. Asiae., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 776, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita chamaeleon [spec. nov.] N. testa sulcata sulcis viginti, labiis dentatis: interiore rugoso tuberculato. Rumph. mus. t. 22. f. L. Valvata 3 undulata. Argenv. conch. t. 10. f. Q. Kratzenst. Regenf. 12. t. 3. f. 26. Habitat in O. Asiae ad Bandam., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 779, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita corona [spec. nov.] N. testae anfractibus coronatis spinis, labiis edentulis. Rumph. mus. t. 22. f. O. Valvata spinosa. Pet. amb. t. 3. f. 4. Argenv. conch. t. 10. f. 2. Habitat in Asiae fluviis., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 777, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita [gen. nov.] Animal Limax. Testa univalvis, spiralis, gibba, subtus planiuscula. Apertura semiorbicularis: labio columellae transverso, truncato, planiusculo. * Umbilicatae., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 776, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

Nerita undata [spec. nov.] N. testa sulcata sulcis triginta, labiis dentatis: interiore rugoso tuberculato. Rumph. mus. t. 22. f. 4. Gvalt. test. t. 66. f. X. Habitat in O. Asiae ad Amboinam. Differt a praecedenti etiam apice magis prominente, & fasciis latiusculis, nec tenuibus striis., Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 779, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206

The indications of Purbeck deposits in this neighbourhood, although the beds are neither very extensive nor of any great thickness, are more clearly defined than has been generally supposed. There area bout thirteen feet of strata decidedly freshwater, containing Cypris, Paludina, Planorbis, and remains of vegetables, chiefly Thuytes and small seed-vessels. The western end of the great quarry at Swindon presents the following section in descending order: There can be no doubt therefore that these beds are representatives on a small scale of a portion of the Purbeck formation. The surface of the Portland strata has been greatly denuded previously to the deposition of the overlying group, for in many cases the latter is deposited in hollows and cavities where the Portland sand has suffered erosion by water, on which it reposes at very irregular intervals. The top of the Portland oolite is composed chiefly of whitish sand containing layers of Trigonia and other marine shells, and this includes harder nodules full of shells, chiefly Trigonia incurva , Lucina Portlandica , Cytherea rugosa and Nerita angulata , often retaining their shelly covering though decomposed and friable. These masses too are very unevenly dispersed. No. 5 in the section, which in its lower part is highly carbonaceous and resembles vegetable mould, is to al appearance a kind of ‘dirt bed,’ and may be considered as the representative of one the dirt beds in the islands of Portland and Purbeck. It also contains numerous small pebbles which are likewise found in it on the coast