History of British animals - University of Guam Marine Laboratory

27S MOLLUSCA. PULMONIFERA. Planorbis.122. P. albus.— Concave on both sides, striated transverselyand longitudinally;aperture oblique, dilated.Mull. Verm. ii. 164.— Helix umbilicata quatuor anfractibus apertura subrotunda,Walk. Test. Min. 5. tab. 1. l!)— Helix alba, Mont. Test. Brit.459. Supp. tab. xxv. f. 7 —P. bispidus, Drop. Moll. 43—In ponds, common.Breadth about a quarter of an inch ; whorls four, last whorl greatly largerthan the preceding one, slightly depressed ; aperture entire ; lower-lip joiningthe body, ascending the ; upper-lip advanced.123. P. nautilus. — Shell flat above, concave below, withtransverse ridges, which, on the margin, form a spinous ridge.Turbo Nautilus, Linn. Syst.i. 1241—P. imbricatus, Mull. Verm. ii.165 Helix, Walk. Test. Min. 6. t. i. f. 20, 21.—Turbo Naut. Mont.Test. Brit. 466. Supp. t. xxv. f. 5—In ditches in England, common.Breadth |th of an inch ; whorls four, flat, but well defined by the separatingline ; below, a deep cavity, exhibiting more rounded whorls ; aperture entire,suborbicular. As the transverse ridges are partly cuticular, they areliable to be rubbed off.124. P. nitidus.— Glossy; a central cavity on both sides ;aperture interrupted by the preceding whorl.Mull. Verm. ii. 163 Helix fontana, Lightfoot, Phil. Trans. 1786, 165.t. 11. f. 1, 4. Mont. Test. Brit. 462. t. vi. f. 6—In ditches, Englandand Scotland.eBreadth about T 5 ths of an inch ; nearly equally convex on both sides ;above, the body-whorl is highest on its central edge, sloping downwards tothe exterior margin the shallow central ; cavity exhibits the preceding whorls ;below, the body-whorl is nearly flat, and the deep central cavity scarcely displaysthe preceding whorl ; aperture subtriangular, the lips on both sides embracingthe body-whorl.** Whorls carinated-125. P. vortex.— Whorls six or seven; slightly concave above;beneath flat.Cochlea exigua subfusca, List. An. Ang. 145. Conch, t. 138. f. 43. — Helixvort. Linn. Syst. i. 1243 Planorbis vort. Mull. Verm. ii. 158.—H. vort. Penn. Brit. Zool. iv. 133. Mont. Test. Brit. 454. t.Supp. xxv.f. 3 In ditches, England and Ireland.Breadth §tbsof an inch ;whorls increasing gradually, narrow, broadest onthe under side ; slightly carinated near the lower edge ; mouth subtriangular.In itsyoung state, this seems to be the Helix rhombea of Dr Turton, Conch.Diet. 47.126. P. complanatus.— Whorls five, carinated at the loweredge above, ; nearly concave ; beneath slightlyflat.Helix comp. Linn. Syst. 1242.— Plan, umbilicatus, Mull. Verm, 160—H. comp. Mont. Test. Brit. 450. Supp. t. 25. 3.— f. P. marginatus, Drap.Moll. 45 In ponds and ditches, common.Breadth upwards of half an inch ; whorls increasing so as to form a slightconcavity rounded ; ;line of separation deep close ; upon the under margin isthe keel, which does not enter the subquadrangular aperture ; the whorls belowslightly rounded ;lines of growth distinct ;tentacula dusky, dark in themiddle.