PATELLA. LIMPET. 
138 
of the crown, or inside markings. The error originated in 
Da Costa, who considered the P. laevis to he the old shell of 
P. pellucida: and this error has been more or less confusedly 
continued ever since. Even Mr. Dillwyn, who makes them 
distinct, has quoted the figure 6 , in Da Costa's first plate, 
and which is the P. laevis, for P. pellucida; and Donovan’s 
plate 3. fig. 1. which is P. pellucida, for P. Ice vis. 
On the leaves of Fuci. v. v. 
S. Patella lacustris. River Limpet, 
Lister , pi. 141. f. 39 — Da Costa, pi. 2. f. 8 — Donovan, 
pi. 147 —Dorset Cat. pi. 22. f. 8 . 
Shell oval, rather conic, very thin, transparent, horn-co. 
lor, covered with a dusky green or dark rough skin, white 
when dead, very obscurely striate longitudinally with often 
a few transverse wrinkles, glossy within and white or 
blueish ; crown not quite central, slightly booked, ending 
in an obtuse point: length three-eightlis of an inch j breadth 
a quarter; height not a quarter. 
In rivers, attached to stones, v. v, 
*). Patella Extinctorinm. Extinguisher Limpet. 
Shell exactly conic, brownish horn-color and rather 
rough, semitransparent, with a few irregular circular wrin- 
lries ; the point rather obtuse, quite erect and central, 
without curvature or apparent volution j the base orbicu¬ 
lar, with the margin thin and plain ; inside glossy brown¬ 
ish-white : diameter of the base the tenth of an inch 5 
height about a third more than the diameter. 
A living specimen of this curious and very distinct mi¬ 
nute Patella we took from a mass of the Serpula tubularia, 
trawled up at Torbay. Its figure exactly resembles a com¬ 
mon extinguisher: and independently of its regularly conic 
shape and comparatively contracted base, it maybe known 
from the P. Chinensis by the want of internal appendage 
or lip. v. v. 
10. Patella oblonga. Oblong Limpet. 
Donovan, pi. 150 —Dorset Cat. pi. 18. f, 20*, and pi. 22. 
f. 8 . a. 
Shell oblong, contracted in the middle, very thin and 
transparent, 
