CONCHOLOGY. 



65 



Univalves. 



Genus I. Patella. Limpet. 



i. Shell subcorneal, month large basin-shaped. 



Obs. The inhabitants of this genus resemble the Li- 

 maces of the mollusca order of Linnaeus. The species 

 admit of distribution into six subdivisions, -which La- 

 treille has constituted into as many genera. 



A. Suborbicular, simple beneath, vertex entire, mar- 

 gin destitute of fissures. Patella. 



1. Vulgala. Common Limpet. Shell subcorneal, 

 •with about fourteen obsolete angles, vertex nearly cen- 

 tral, mouth subovate, margin indented ; diameter about 

 two inches. 



Brit. Zool. tab. 89. fig. 145, 146. 

 This species is subject to numerous variations in co- 

 lour and shape. The young shells are flat, with deeply 

 indented margins and a lateral vertex. The old shells 

 are usually smoother, more conical, and have the vertex 

 nearly central. This is a very common shell, adhering 

 to rocks and stones. 



2. Ccerulea. Shell translucent, subovate, slightly 

 wrinkled concentrically, and rayed with bluish lines 

 from the vertex to the margin ; vertex nearly central, 

 protuberant, worn, margin waved ; inside glossy, pa- 

 vonine; length an inch, breadth eight-tenths, height 

 five-tenths. 



Brit. Zool tab. 90. fig. 151. 

 Test. Brit. Sup. page 132. 

 In the young state this shell is depressed, the vertex 

 is protuberant and lateral. In the vertex two small 

 spots of a black colour may sometimes be observed ; 

 such shells have been hastily constituted into a distinct 

 species under the title P. bimaculafa. This species is 

 common in England and Scotland. It feeds on the 

 stalks of Fucus digitatus, in which it forms a circular 

 cavity. 



3. Pellucida. Shell thin, horn coloured, rayed with 

 dotted lines of azure, most conspicuous from the vertex 

 to the broadest end, oval, rounded at top, with an ob- 

 scure vertex at the narrow end of a black colour ; mar- 

 gin entire even ; length about an inch, breadth five- 

 eighths, height three eighths. 



Brit. Zool. tab. 90. fig. 150. 



Pult. Dorset, tab. 33. fig. 5. 



British Shells, tab. 3. fig. 1. 1. 1. 

 This shell varies a little in its markings. Limifeus 

 states the number of coloured rays at four. In young 

 specimens we have observed them entirely wanting, 

 their place being supplied by brown lines. In the oldei 

 specimens they sometimes exceed thirty, and the shell 

 is furnished with obsolete ribs. Common on the coast 

 of England and Scotland. 



4. Elongata. Shell pale brownish white, with darker 

 coloured obsolete rays, opake, dull, somewhat pointed 

 before, vertex rounded ; length three-tenths, breadth 

 two-tenths, height one-tenth. 



A new species found at St Andrew's, Fifeshire, by 

 Miss Lambert. 



5. Parva. Shell reddish white, with about sixteen 

 pale reddish lines from the vertex to the margin, out- 

 side dull, inside glossy, subcorneal, oval, slightly wrink- 

 led concentrically ; vertex a little pointed, approaching 

 the narrow end; length about four-tenths, breadth three- 

 tenths, height one-eighth of an inch. 



Brit. Shells, tab. 21. fig. 2. 

 Pult. Dorset, tab. 14. fig. 11. 

 Frequent on rocks and stones about low- water mark. 



6. Elliptica. Shell elliptical, margin entire, vertex a 

 VOL. VII. tart 1. 



little pointed, strong, dull, opake ; length four-tenths. Univalves, 

 breadth three-tenths, height scarcely two-tenths. ^^ "Y"^"' 



This shell resembles the preceding species, and may 

 be easily mistaken for it. The dullness, opacity, and 

 want of coloured lines, are the marks by which it maybe 

 distinguished. A new species found on stones in Zetland. 



7- Distorta. Shell subquadrangular, depressed, wrink- Distorta, 

 led. colour brown, destitute of lustre, vertex nearly cen- 

 tral, small, margin uneven, flattened; length five-tenths, 

 breadth four-tenths, height two-tenths. 



A new species found adhering to stones dredged in 

 deep water off the coast of Zetland. 



8. Rota. Shell white, opake, round, with a regular- Rota, 

 ly toothed margin. 



Test. Min. Rar. tab. 1. fig. 16. 



A minute species from Sandwich, rare. 



B. Oblong, vertex pointed and leaning on the mar- 

 gin. Crcpidula. 



9- Intorta. Shell ovate, with upwards of twenty Intorta, 

 equidistant tuberculated ribs, and alternate, obsolete, 

 smaller ones ; vertex towards the narrow end, and turn- 

 ing downwards, margin slightly indented with the ribs; 

 length three-fourths of an inch, breadth about half an 

 inch, the height somewhat less. 



Brit. Zool. tab. 90. fig. 148. 

 Brit. Shells, tab. 146. 



First found in Anglesea by Mr Pennant, and since 

 on the coast of Devon and in the Frith of Forth by Mr 

 Laskey. 



10. Lacuslris. Shell entire, oval, subcorneal, vertex .Lacustris 

 near to one end, hooked, mouth oval, margin even and 



thin, inside glossy, outside covered with a dark green epi- 

 dermis; length three eighths, breadth two eighths, height, 

 not quite so much. 



Pult. Dorset, tab. 22. fig. 8. 8. 



Brit. Shells, tab. 147. 

 Common in rivulets adhering to stones, seldom to the 

 leaves and stalks of aquatic plants. 



11. Oblonga. Shell en tire, membranaceous, pale horn Oblong-a, 

 coloured, oblong, compressed ; vertex pointed, turned to 



one side, mouth oval, margin entire, inside smooth, 

 glossy, outside covered with a brownish epidermis ; 

 length four eighths, breadth two eighths, and height 

 one eighth. 



Phil. Trans, vol. lxxvi. tab. 3. fig. 1, 2, 3, 5 



Pult. Dorset, tab. 18. fig. 20. 



Brit. Shells, tab. 150. 

 On plants, in ditches, and ponds ; not uncommon. 



C. Oval, summit produced into a beak, somewhat 

 twisted, and reclining towards the left margin. Con- , 

 cholepas. 



12. Anliquata. Shell thick, opake, white, subcorneal, Antiquata, 

 with concentric imbricated wrinkles, vertex obliquely 

 pointing upwards, or extending and recurved ; mouth 



oval, about half an inch w 7 ide; 



Test. Brit. tab. 13. fig. 9. 

 Pult. Dorset, tab. 22. 72. 

 First observed at Weymouth by Mr Bryer, and after- 

 wards in the Frith of Forth by Mr Laskey. 



13'. Hungarica. Shell conical, striated, acumina- Hwarica, 

 ted ; vertex reflected, terminating in a spiral turn un- 

 derneath ; mouth circular, about an inch in diameter ; 

 margin waved ; epidermis of a brown colour, with a 

 ciliated border ; height five eighths of an inch. 

 Brit. Zool. tab. 90. fig. 147. 

 Brit. Shells,, tab. 21. fig. 1. 1. 

 Not uncommon on the west coast of England, and 

 the east coast of Scotland. 



