91 



CON CHO LOGY. 



Bivalve;. 



Irus, 



CaUanea, 



XXXVII. 



Venus. 



Papliia, 



Verrucosa, 



■Laroinosa, 



•'Striatula, 



5. Irus. Shell sub-oval, opake, rugose, with high 

 concentric membranaceous ridges, reflecting upwards, 

 broken or undulated ; interstices finely striated ; umbo 

 small, placed near one side ; apex much turned ; teeth 

 small, bifid; margin plain; length halt* an inch, bread th 

 three quarters. 



Brit. Shells, tab. 29. fig. 2. 

 Found frequently on the western coast of England 

 burrowed in limestone. 



6. Gastanea. Shell -strong, glossy, chesnut-coloured, 

 furnished with a few irregular transverse "wrinkles; a 

 ray of chesnut runs from the beak to the opposite mar- 

 gin, in a ciuwed direction ; beak obtuse, inclining to the 

 anterior side ; one large and one small tooth in each 

 valve; no lateral teeth; margin plain; length a quarter 

 of an inch, breadth three-eighths. 



Test. Brit. tab. 17. fig. 2. 

 Discovered by Mr Montagu in St Austle's bay, Corn- 

 wall ; and found by Mr Laskey at Dunbar. 



7. Rubra. Shell smooth, of a reddish colour, cunei- 

 form, truncated at one end; beak obtuse; inside of the 

 same colour ; margin plain ; hinge with two teeth in 

 each valve, placed angularly, and approximating at the 

 beak; very minute, not a line in length. 



Test. Brit. Sup. p. 38. 

 Discovered by Mr Montagu among Corallines,^ deep 

 water. 



Genus XXXVII. Venus. 



Shell equivalve, the frontal margin flattened with in- 

 cumbent tips ; hinge with three approximate and diver- 

 ging teeth. 



1. Paphia. Shell strong, flattened, sub-orbicular, 

 witli several elevated broad concentric ridges variously 

 coloured ; beak central, much turned to one side, be- 

 neath which is a cordiform depression ; hinge with 

 strong teeth ; margin crenulated ; length and breadth 

 about an inch. 



• Brit. Shells, tab. 170. 

 Found on the British shores from Cornwall to Zetland. 



2. Verrucosa. Shell strong, thick, heavy, sub-orbi- 

 cular,- convex, with numerous strong elevated ridges, 

 somewhat recurved and broken at the ends ; umbo 

 turned much to one side, beneath which is a cordiform 

 depression ; cartilage slope of the right valve turns in- 

 wards, slightly striated longitudinally and marked 



• transversely with brown streaks ; margin crenated ; di- 

 ameter about two inches and a quarter. 

 Brit. Shells, tab. 44. 



■ Brit. Zool. tab. 54. fig. 48. Venus Erycina. 

 Common on many of the British shores. 



3. Lamirtosa. Shell ovate, with concentric thin lami- 

 nal ridges, very little reflected ; striated in a longitudi- 

 nal direction between the ridges at the umbonal region ; 

 beak pointed inclining to one side with a cordiform de- 

 pression ; hinge with four teeth in each valve ; margin 

 finely crenated ; length about an inch, breadth an inch 

 and a quarter. 



Brit. Shells, tab. 115. 

 Mem. Wer. Soc. vol. i. tab. 8. fig. 16. 

 Found on the coast of Devonshire by Mr Montagu, 

 and in the Frith of Forth by Mr Laskey. 



4. Striatula. Shell strong sub-cordated with nume- 

 rous fine prominent recurved concentric striae ; yellow- 

 ish, rayed with rufous brown, and frequently marked 

 with fine zigzag streaks of the same colour; umbo turns 

 to one side, beneath which is a cordiform depression ; 



-cartilage slope much depressed, faintly striated; margin 



crenated; length an inch, breadth an inch and a quar- Bi values. 



Brit. Zool. tab. 56. fig. 50. 

 • Brit. Shells, tab. 68. 

 In sandy bays frequent in company with the common 

 cockle. 



5. Islandica. Shell strong, thick, sub-orbicular, con- Islandioa,. 

 vex, white, with a dark brown epidermis ; wrought with 



fine irregular concentric striae; beak pointed, turned 

 inwards, and curved to one side; no depression ; mar- 

 gin plain; length three inches and three quarters; 

 breadth four inches and a quarter. 



Brit. Zool. tab. 53. fig. 47. V. mercenaria. 



Brit. Shells, tab. 77. 

 Common on the British shores. From the Frith of 

 Forth, we have seen one winch was 1 3 inches in cir- 

 cumference, and weighed nine ounces and a half. At 

 St Andrews' they are called Dakies, and in Zetland 

 Cuvies. 



6. Chione. Shell strong, sub-cordated, wrinkled con- Chione, 

 centrically, covered with a very smooth glossy chesnut 

 coloured epidermis more or less radiated with a dark- 

 er shade ; mnbo placed nearest to one end, with the 



apex turned sidewise, beneath which is a strong cordi- 

 form depression ; margin plain ; length three inches, 

 breadth three inches and three quarters. 

 Brit. Shells, tab. 17- 

 Not uncommon on the Cornish coast, where they are 

 called Queens, more rare on the Dorset and Cheshire 

 coasts. 



7. Exoleta. Shell strong, orbicular, with fine close- Exolet.a,. 

 set, thread-like, concentric striae, with a few obsolete 

 ridges ; umbo much turned to one side, beneath which 



is a short much depressed cordiform depression ; margin 

 plain ; diameter two inches. 



Brit. Zool. tab. 54. fig. 49. 



Brit. Shells., tab. 42. fig. 1. 

 Not uncommon on the British shores. 



8. TJndata. Shell orbicular, thin, white with fine 

 concentric irregular stria 1 , which sometimes run into 

 uneven wrinkles; umbo prominent, apex pointed and 

 tinning to one side; no depression ; inside smooth, con- 

 cave ; margin plain ; edge acute, and somewhat undu- 

 lated ; length an inch and a quarter, breadth an inch 

 and a half. 



Brit. Zool. tab. 55. fig. 51. 



Not unfrequent on the British shores. 



9- Tigeriiia. Shell suborbicular, flat, lenticular, thin, 

 white, striated longitudinally and minutely striated 

 transversely ; beak small, pointed and turning a little 

 to one side ; margin plain ; diameter about three quar- 

 ters of an inch. 



Test. Brit tab. 4. fig. 1. 



First ascertained to be English by Dr Maton, who 

 found it on Studland beach, Dorsetshire, on the North 

 shore, Poole, and at Weymouth. 



10. Sinuosa. Shell thin, convex, with a very deep 

 obtuse sinus, or bending, on the front. 



Brit. Zool. tab. 55. fig. 51. A- 

 Figured by Pennant from the Portland Cabinet. An 

 uncertain species. 



11. Ovata. Shell sub-oval, opake, somewhat compres- 

 sed, with strong longitudinal ribs, transversely striated; 

 umbo nearly central, apex turning a little to one side, 

 beneath which is a subcordiform depression turning a 

 little to one side; margin finely crenated ; length three* 

 eighths of an inch, breadth half an inch* 



Brit. Zool. tab. 56. fig. 56. 

 Pult. Dorset, tab. l.fig. 15. 



Undata, 



Tigerina, 



Sinuosa, 



Ovat^ 





