134 
PATELLA. LIMPET. 
rugged with plaits or scales irregularly folding over each 
other, sometimes only transversely scaly : valves unequal, 
one of them flat and entire, the other very convex; inside 
pearly white : beaks rather oblique, with a row of small 
tooth-like knobs on each side : color generally dull brown. 
Banks and beds at low water mark. v. v. 
13. Ostrea parasitica. Parasitical Oyster. Fig. 8. 
Shell somewhat orbicular, or inclining to oblong, flattish, 
smooth and rather glossy, very obscurely wrinkled trans¬ 
versely, of a paler or darker chocolate-brown color, some¬ 
times inclining to yellowish-brown, with irregular reddisfc- 
brown longitudinal waved lines disposed in the manner 
. of loose tufts ; sometimes there is a single whitish stripe 
from the hinge to the margin; beaks central, nearly 
straight; inside glossy-white, purplish towards the hinge, 
with afewdenticnlations on each side the hinge: diameter 
about an inch and a half. 
Wc And this species not unfrequently attached to the 
claws of crabs, in Devonshire, and in Ireland on floating 
timber, and even on one another. Its habits therefore and 
general appearance incline us to think it quite distinct from 
the common oyster, v. v. 
PATELLA. LIMPET. 
Shell with a single valve, more or less conical 
and shaped like a bason, and generally without 
spire, 
A. Furnished with an internal appendage or partition, 
1 , 2 . 
B. With the crown entire, 3 to 16. 
C. With the crown perforated, 17 to 20. 
A. Furnished with an internal appendage or partition , 
1 , 2 . 
1. Patella Chinensis. Chinese Bonnet. Fig. 29, 30. 
Lister , pi. 546. f. 3.9— Montagu , pi. 13. f. 4. 
Patella albida. Donovan, ph 129. 
Shell 
