Illustrated Index of British Shells / Containing figures of all the recent species

by G. B. Sowerby

Galeomma. Adheres to rocks by byssus.

14, 15. G. Turtoni, Sowb.—Channel Islands, and Exmouth. Oblong, gaping.

Cyclas. Inhabits fresh-water.

16. C. cornea, Linn. (Tellina.)—Sphærium c., Scopoli, C. rivalis, etc.—Ponds and ditches everywhere. Equilateral, subquadrate.

17. C. pisidioides, Gray.—C. cornea, var., Brit. Moll.—Ditches and ponds, C. Oblique, and light coloured.

18. C. rivicola, Leach.—Cardium nux, etc.—Thames, etc. Large, oval, wrinkled.

19. C. caliculata, Drap.-C. lacustris, etc.—Newcastle, Bristol, etc., Mr. With a ridge at the apex.

20. C. lacustris, Drap.—pallida, Gray.—Regent's Park, etc., Mr. Oval, light.

Pisidium. Inhabits fresh-water.

21. P. obtusale, Pfeiffer.—P. pusillum, var.?