141 



Ancylus fluviatilis. Drap. p. 48. t. 2./. 23, 24. 



Brard, p. 200. t. 7. f, 3. 



— ' Sorverbij, Gen. Jig. 1. 



Patella fluviatilis. Mont. p. 482. 

 Patella lacustris. Turt. Diet. p. 138. 



b. with slight longitudinal striae. 



Shell about a quarter of an inch in diameter, and 

 nearly as much in height, semitransparent, light 

 horn-colour, covered with a dusky green skin, 

 slightly marked with concentric striae, inside blue- 

 ish-white, glossy : the crown slightly curved down- 

 wards. 



In streams and rivulets, attached to stones. 



12G. Ancylus /«c?<5^m. Shell oblong, compressed, 

 with the point slightly recurved in an oblique di- 

 rection and nearly central. 



Ancylus lacustris. Drap. p. 47. t. 2./. 25 — 27. 



Sowerhy, Gen.f. 2. 



Patella lacustris. Montagu, p. 484. 

 Patella oblonga. Turt. Diet. p. 138. 



Shell a quarter of an inch long, and hardly a tenth in 

 breadth, extremely thin and transparent, smooth. 



