PATELLA. LIMPET. 
139 
transparent, horn-color, mostly covered with a greenish 
skin, smooth orwery faintly wrinkled transversely, glossy 
within: crown nearly but not quite central, small, pointed, 
slightly hooked in an oblique direction : length a quarter of 
1 a inch j breadth an eighth. 
On aquatic plants, v. v. 
11. Patella tricorais. Three-horned Limpet. 
Shell conic, opalce, brownish-white, rather rough but not 
jtriate nor wrinkled, covered with a brown skin which 
lastly fringes the margin : crown near one end, divided 
irto three white points or tooth-like projections, which are 
cot close together but placed in a triangular or irregular 
1 manner across the shell, and nearly erect: base orbicular ■ 
the inside white, polished, with two tubercular projections 
| corresponding with the lateral points of the crown : dia- v 
1 meter and height about the tenth of an inch. 
I A few specimens of this singular shell we found among 
| tie fine sand at Portmarnock, near Dublin ; and have since 
token it alive, in Devonshire, from the Serpula tubularia. 
At first we had considered them as an accidental lusus ; 
fet a closer examination and comparison with such as are 
in any way allied to them, as P. virginea, I*, laeustns, and 
P. oManga, have convinced us of their identical distinct : on. 
i The crown appears to be spread across the shell, and is 
deeply cloven into three very distinct tooth-like points, 
♦diich have a slight inclination towards the larger side of 
the shell, and are sometimes placed in a triangular position. 
Hey are much stronger, and more orbicular at the base 
than P. virginea, and the inside is of a clear polished white, 
r.f. 
12. Patella antiquata. Antiquated Limpet. 
litter,pi. 544. f. 30, and 31— Montagu , pi. 13. f. 9. 
Patella Mitrula. Dorset Cat. pi. 22. f. /. a. 
'Shell thick, strong, nearly epake, white, conic, marked 
with concentric scale-like wrinkles, which are mostly very 
strong towards the margin and incumbent on each other : 
crown sometimes pointing a little obliquely, sometimes ex¬ 
tended and very slightly recurved, often obtuse, and nearer 
one end ; the base roundish-oval: diameter about an inch. 
Weymouth, and the south of Ireland : rare. v. m. 
13. Patella 
