S2 



CONCHOLOGY. 



Univalve', 



Kluviatilis. 



Glaucina, 



CaKrtna, 



$£it'n3a, 



I'aUidula,. 



Tuberosis. 

 lira?, 



gufa, 



FxJlucida, 



Alba. 



eel ; whorls five, the first large, the others small and 

 placed laterally ; mouth sub-orbicular ; margin thicken- 

 ed within, the edge sharp ; length three quarters of an 

 inch. 



Brit. Zool. tab. 87. fig. 143. 



Brit. Shells, tab. 20. fig. 2. 

 Extremely common on all the British shores, creep- 

 ing on stones a little below high water mark. 



2. Fluviatilis. Shells sub-pellucid, sub-oval, elegant- 

 ly spotted'; whorls three, the first very large, the others 

 small, but well defined and placed laterally ; apex mi- 

 nutely small ; mouth lunated ; outer lip thin ; pillar 

 lip broad, flat, and white ; length three- eighths of an 

 inch. 



Brit. Shells, tab. 16. fig. 2. 

 Found in England in slow running rivers adhering 

 to stones. 



B. Base perforated. Natica. 



3. Glaucina. Shell strong, smooth, glossy, vari- 

 ously coloured ; whorls six, the first ventricose ; apex 

 pointed; mouth suboval, outer lip thin, even; pillar 

 lip thick, reflected, forming a large and deep pillar 

 cavity : length an inch and a half. 



Brit. Zool. tab. 87. fig. 141. 

 Brit. Shells, tab. 20. fig. 1. 

 On the British shores, common, from Devonshire to 

 Zetland. 



4. Canrena. Shell resembling the last, but in this 

 the pillar cavity is furnished with two spiral ridges and 

 two grooves ; diameter about half an inch. 



British Shells, tab. 167. N\ intricata. 

 First noticed as British by Mr Donovan, whose spe- 

 cimens are from Weymouth. 



5. Nilida. Shell ovate, white, smooth, shining ; 

 spire short ; mouth oval, gibbous beneath ; the pillar 

 cavity half closed ; diameter scarcely half an inch. 



Brit. Shells, tab. 144. 



First ascertained to be British by Mr M'Leay, who 

 found small specimens on the coast of Caithness, and 

 we have observed it at St Andrew's, Fifeshire, and in 

 Zetland. 



C. Pallidula. Shell sub-pellucid, light brown, with 

 three whorls, the first very large ; epidermis rough, 

 brown ; mouth semilunated, outer lip thin, fringed by 

 the epidermis ; pillar lip thick, white, concave, and 

 perforated; inside glossy; length scarcely half an inch. 

 Brit. Shells, tab. 16. fig. 1. 



In England rather rare. Common on the Scottish 

 coast, in Orkney and Zetland. 



7. Tuberosissima. Shell pellucid, white, with four 

 whorls ; on the body whorl are four elevations broken 

 into tubercles ; pillar cavity large ; diameter one eighth 

 of an inch. 



Test. Brit. tab. 29. fig. 5. 

 Found by Mr Laskey in the Frith of Forth. 



8. Rufa. Shell smooth, glossy, of a livid purplish 

 colour, with a white band round the top of the volu- 

 tions, and two others on the body whorl; diameter 

 more than half an inch. 



Test. Brit. tab. 30. fig. 3. 

 Found near Dunbar, Haddingtonshire, by Mr Las- 

 key. 



9. Pellucida. Shell smooth, pellucid, with three vo- 

 lutions. 



Lin. Trans, vol. iii. page 67. 

 Found by Mr Adams on the Pembrokeshire coast. 

 10.. Alba. Shell smooth, sub-pellucid, with two vo- 

 lutions; 



Lin. Trans, vol. iii. page 67. 

 Found by Mr Adams along with the preceding spe- 

 cies. These two species are probably the fry of N. 

 glaucina. 



Univalves. 



Genus XVIII. Trochus. 



Shell more or less conical; aperture somewhat angu- xvill 

 lar, transversely contracted, with an oblique axis. Thochvs. 



Obs. Lamarck has separated from this genus those 

 shells which have the pillar cavity erenulated or denti- 

 culated at the margin of the windings, and those which 

 have a round opening with the two margins disunited, 

 and a pillar truncated at the base forming a tooth pro- 

 jecting into the opening. The former he terms Sola- 

 rium, the latter Monodonta. 





A. Base perforated. 



1. Magus. Shell with five or six tumid, sub-de- Magus,. 

 pressed whorls, well divided by the separating line, 



and wrought with fine spiral ridges ; mouth compress- 

 ed, angulated ; pillar cavity large, deep, and grooved ; 

 diameter about an inch. 



Brit. Zool. tab. 80. fig. 107. 



Brit. Shells, tab. 8. fig. 1. 

 Not uncommon on the British shores from Devon- 

 shire to Zetland. 



2. Cinerarws. Shell ' irregularly conical, spirally Cinareihis, 

 striated, with four or five volutions not much raised ; 



colour cinererius marked with undulated lines of 

 brown ; mouth angulated ; pillar cavity small but deep ; 

 inner lip a little reflected ; diameter about five-eighths 

 of an inch. 



Brit. Shells, tab. 74. the upper and two lower 

 figures. 



On the British coast common. 



3. Umbilicaius. Shell strong, flattish, rounded at Umhiliea 

 the top, not pointed ; whorls five, nearly even, with ob- tus ' 

 solete striae waved with lines of a light or dark purple ; 

 mouth compressed, angulated ; pillar cavity large, deep; 

 diameter three quarters of an inch. 



Brit. Zool. tab. 80. fig. 106. 

 Found in similar situations with the last, and equally 

 abundant. 



4. Tumidus. Shell strong, subconic, tumid, with four Tumidusw 

 whorls, wrought with fine close set spii-al stria;, inter- 

 rupted only by a deep separating line; body whorl 

 flattened and subcarinated ; pillar cavity small, and 



in old specimens frequently closed; mouth sub-qua- 

 drangular; diameter about a quarter of an inch. 

 Test. Brit. tab. 10. fig. 4. 

 On the English shores rare. Plentiful in Orkney 

 and Zetland. 



5. Terrestris. Shell thin, conic, with six flat longi- Terrestris, 

 tudinally striated whorls, with a prominent ridge at the 



base of each ; mouth compressed angulated ; base flat, 

 perforated, striated from the centre. 



Brit. Zool. tab. 80. fig. 108. . ' 



Brit. Sheik, tab. 111. 

 Found by Hudson on the mountains of Cumberland, 

 and by Mr Morton in Northamptonshire. 



6. Fuscus. Shell five spired^ marginated, aperture Fustns, 

 roundish, with a pillar cavity. 



Test. Min. Rar. tab. 2. fig. 58. 

 From Sandwich, common ; Mr Walker. 



B. Base imperforated. 



7- Crassus. Shell subconic, with five rounded vo- grassus, 

 lutions, closely set with zigzag lines ; mouth rounded 



