gS6 
MOLLUSC A. 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 pink 
colour. Anteal tentacula, shorter than the superior ones, which have the 
eyes behind. Three filiform branchiae in each bundle. ' 
Gen. XLI. VALVATA. — Shell spiral; aperture circular, 
operculated. Branchiae single, plumose issuing from the 
neck. 
151. V. cristata. — Shell depressed, of three or four whorls, 
nearly flat above, concave below. 
Mull. Verm. ii. 198 — Helix cornea quatuor anfractibus apertura rotun- 
da, Walk. Test. Min. 5. t. i. f. 18. — Helix exist. Mont. Test. Brit. 
460. fig. i. f. 7, 6* — Iw rivers and ditches, England. 
Breadth about ^^th of an inch, light horn-coloured ; whorls rounded, in- 
creasing. gradually, slightly wrinkled across ; the central cavity exposes all 
the whorls ; aperture attached to the body-whorl, but not interrupted by it ; 
operculum spirally striated. Animal dusky, tentacula three, two placed in 
front, at the base of which are the eyes, and one on the right side, corres- 
ponding with the branchia, setaceous and produced. Front emarginate. 
152. V. piscinalis. — Shell turrited, whorls four or five, round- 
ed, with a large central cavity. 
Nerita pis. Mull. Verm. ii. 172. — ^Turbo tribus anfractibus, umbilicatus 
apertura subrotunda. Walk. Test. Min. 15. t. ii. f. 56.— Turbo fonti- 
nalis, Mont. Test. Brit. 348. t. xxii. f. 4. — In lakes and slow running 
streams, common. 
Breadth and height about a quarter of an inch. Whorls increasing rapid- 
ly, yellowish-brown, distinctly striated across ; central cavity distinct, but 
not large ; apex obtuse ; aperture orbicular, lip thin, slightly attached to the 
body-whorl ; operculum spirally striated, with a central knob. Animal like 
the last. 
Gen. XLII. PATELLA. Limpet. — Shell entire, conical; 
snout with two pointed tentacula, with eyes at the base ; 
tongue long, strap-shaped, covered with three rows of in- 
terrupted reflected short spines. 
153. P. milgata. Common Limpet. — Shell with about four- 
teen obsolete angles ; apex nearly central, blunt. 
P. ex livido cinerea, striata. List. An. Ang. 195. ; Conch, t. dxxxv. 14. 
P. vul. Linn. Syst. i. 1258. Mmt. Test. Brit. 475. — Common on 
rocks, near Ioav water-mark. 
Shell sometimes inches long, and 2 inches broad in the aperture, and 1| 
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 the 
thickness. Foot oval, snout subcylindrical ; margin of cloak fringed ; bran- 
chial circle 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 ; apex 
prominent, submarginal, and slightly decurved. 
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