280 MOLLUSCA. PULMONIFERA. Segmentina. 



Gen. XXXIV. ANCYLUS— SheU conical; foot short ; tenta- 

 cula short, flat, and a Httle truncated. 



129. A.yiuviatiUs. — Aperture suborbicular ; apex lateral. 



Patella fluviatilis, List. An. Ang. 151. Conch. 1. 141, £ 39. — P. lacustris, 



Linn. Syst. i. 1260 An. fluv. Mull. Verm. ii. 201.— P. fluv. Mont. 



Test. Brit. 482. Don. Brit. Shells, t. 147 — On stones in rivulets, 

 common. 

 Length about fths, breadth |ths of an inch ; height nearly equal to the 

 breadth ; horn-coloured, with concentric wrinkles crossed by faint lines ; apex 

 pointed, a little recurved. 



130. A. lacustris. — Aperture oblong ; apex nearly central. 



Mull. Verm. 199 — Patella oblonga. Light. PhiL Trans. 178G, 168. t. 111. 



f. 1, 6 P. lac. Mont. Test. Brit. 484. Don. Brit. Sh. t. 150.— On 



plants in ditches and lakes. 

 Length ith of an inch ; breadth ith, height scarcely j'oth of an inch, thin> 

 smooth, greenish, compressed; apex low, pointed, recurved. 



EXTINCT SPECIES. 



1. A, elegans. — Convex, subconical ; aperture longitudinally obovate ; apex 

 oblique, eccentric, near the narrowest part of the aperture. — Sower. Min. 

 Conch, t. 533 — Found in dark-grey sand of the London clay, at Hordwell, by 

 Charles Lyell, Esq. jun. 



