ANCYLUS. 
219 
vegetable matters. They are timid, rarely change 
their places, walk very slowly, and do not swim. 
The eggs are ovoid, hyaline, four or eight, placed 
in a row in a horny, mucous, orbicular, depressed, 
transparent capsule attached to solid bodies. 
Teeth (30, 1, 30) central, much compressed, apex 
with a single sharp point ; lateral teeth bent and 
hooked, the first simple, the last contracted at the 
bend and denticulated. (Figured by Otto Goldfuss^ 
49. t. 7. f. n. ; and Weigmann^ Arch, 1836, t. 10. f. 
9 — 11.) 
It is no proof that the animals do not breathe free 
air because they are usually observed attached to 
stones, like Patellcc^ at the bottom of the water ; for 
Limnceus pereger is more frequently found at the 
bottom of the water on the mud than in any other 
place, and I have seen a specimen in exactly the 
same place for several days without moving. But 
the Ancyli are often found, as has been observed by 
Mr. J effreys, out of the water, and only within reach 
of the spray of a waterfall. 
98. 1. Ancylus fluviatilis. Common River Lim- 
pet.— Shell conoid, with the point recurved 
and near one end; aperture roundish-oval, 
disk bluish. 
Ancylus fluviatilis. Muller^ Verm. ii. 201.; Drap. Hist. p. 48. 
t. 2. f. 23, 24.; Brard, p. 200. t. 7. f. 3.; Sowerhy, Gen. 
fig. 1.; Turton, Man. ed. 1. t. 140. f. 125.; Forbes and Han- 
ley, B. M. iv. 186. t. 122. f. 4. ; Clark, Aim. and Mag. N. H. 
XV. 278. — Patella fluviatilis. Lister; Da Costa, B. C. i. 
t. 2. f. 8. ; Mont. p. 482. — Patella lacustris. Linn. S. N. 
1260.; Turt. Diet. p. 138. — Crepidula lacustris. Fleming, 
Ency. — Ancylus simplex ; A. Janii ; A. gibbosus ; A. cycle- 
