History of British animals - University of Guam Marine Laboratory

280 MOLLUSCA. PULMONIFERA. Segmentina,Gen. XXXIV. ANCYLUS.—Shell conical; foot short ;tentaculashort, flat, and a little truncated.129- A.jluviatilis.— Aperture suborbicular ;apex lateral.Patella fluviatilis, List. An. Ang. 151. Conch. 1. 141, f. 39.—P. lacustris,Linn. Svst. 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 fths of an inch ; height nearly equal to thebreadth ; horn-coloured, with concentric wrinkles crossed by faint lines ; apexpointed, a little recurved.130. A. lacustris.— Aperture oblong;apex nearly central.Mull. Verm. 199—Patella oblonga, Light. Phil. Trans. 1786, 168. t. 111.6—P. lac. Mont. Test. Brit. 484. Don. Brit. Sh. t. 150—Onf. I,plants in ditches and lakes.Length ith of an inch ; breadth |th, height scarcely y^th of an inch, thin*smooth, greenish, compressed; apex low, pointed, recurved.EXTINCT SPECIES.1. A. elegans.— Convex, subconical ; aperture longitudinally obovate ; apexoblique, eccentric, near the narrowest part of the aperture —Sower. Min.Conch, t. 533 Found in dark-grey sand of the London clay, at Hordwell, byCharles Lyell, Esq. jun.