History of British animals - University of Guam Marine Laboratory

286 MOLLUSCA. BRANCHIFERA. Valvata.Flem. Phil. Zool. ii. 470. t. iv. f. 2—Frith of Tay.Length about an inch, slender, pointed behind, rounded in front, of a pinkcolour. Anteal tentacula, shorter than the superior ones, which have theeyes behind. Three filiform branchiae in each bundle.Gen. XLI. VALVATA. — Shell spiral;aperture circular,operculated. Branchiae single, plumose issuing from theneck.151. V. cristata.— Shell depressed, of three or four whorls,nearly flat above, concave below.Mull. Verm. ii. 198.—Helix cornea quatuor anfractibus apertura rotunda,Walk. Test. Min. 5. t. i. f. 18—Helix exist. Mont Test. Brit.460. fig.i. f. 7, 8. — In rivers and ditches, England.Breadth about T'n th of an inch, light horn-coloured ; whorls rounded, increasinggradually, slightly wrinkled across the central ; cavity exposes allthe whorls ; aperture attached to the body-whorl, but not interrupted by it ;operculum spirally striated. Animal dusky, tentacula three, two placed infront, at the base of which are the eyes, and one on the right side, correspondingwith the branchia, setaceous and produced. Front emarginate.152. V. piscinalis.— Shell turrited, whorls four or five, rounded,with a large central cavity.Nerita pis. Mull. Verm. ii. 172—Turbo tribus anfractibus, umbilicatusapertura subrotunda, Walk. Test. Min. 15. t. ii. f. 56.—Turbo fontinalis,Mont. Test. Brit. 348. t. xxii. f. 4—In lakes and slow runningstreams, common.Breadth and height about a quarter of an inch. Whorls increasing rapidly,yellowish-brown, distinctly striated across ; central cavity distinct, butnot large; apex obtuse ; aperture orbicular, lip thin, slightly attached to thebody-whorl ;• operculum spirally striated, with a central knob. Animal likethe last.Gen. XLII. PATELLA. Limpet.—Shell entire, conical;snout with two pointed tentacula, with eyesat the base ;tongue long, strap-shaped,covered with three rows of interruptedreflected short spines.153. P. vulgata. Common Limpet.— Shell with about fourteenobsolete angles;apex nearly central, blunt.P. ex livido cinerea, striata, List. An. Ang. 195. ; Conch, t. dxxxv. 14.P. vul. Linn. Syst.i. 1258. Mont. Test. Brit. 475 Common onrocks, near low water-mark.Shell sometimes 2\ inches long, and 2 inches broad in the aperture, and \\inch in height. It is subject to great variation in the height of the apex,the elevation and number of the markings, the form of the aperture, and thethickness. Foot oval, snout subcylindrical ;margin of cloak fringed ; branchialcircle complete—This species is of great value as a bait in onr fisheries,and even as an article of food.154. P. intorta.— Shell with numerous rough ribs ;apexprominent, submarginal, and slightly dccurved.3