PATELLA. LIMPET. ],39 



transparent, horn-color, mostly covered with a greenish 

 skin, smooth or very faintly wrinkled transversely, glossy 

 within : crown nearly but not quite central, small, pointed, 

 slightly hooked in an oblique direction : length a quarter of 

 an inch ; breadth an eighth. 

 On aquatic plants, v. v. 



11. Patella tricornis. Three-horned Limpet. 



Shell conic, opake, brownish-white, rather rough but not 

 striate nor wrinkled, covered with a brown skin which 

 mostly fringes the margin : crown near one end, divided 

 into three white points or tooth-like projections, which are 

 hot close together but placed in a triangular or irregular 

 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- 

 meter and height about the tenth of an inch. 



A few specimens of this singular shell we found among 

 the fine sand at Portmarnock, near Dublin ; and have since 

 taken it alive, in Devonshire, from the Serpula tubularia. 

 At first we had considered them as an accidental lusus ; 

 but a closer examination and comparison with such as are 

 in any way allied to them, as P. virginea, P. lacustris, and 

 P. oblonga, have convinced us of their identical distinct ! on. 

 The crown appears to be spread across the shell, and Is 

 deeply cloven into three very distinct tooth-like points, 

 which have a slight inclination towards the larger side of 

 the shell, and are sometimes placed in a triangular position. 

 They are much stronger, and more orbicular at the base 

 than P. virginea, and the inside is of a clear polished white. 

 v. v. 



12. Patella antiquata. Antiquated Limpet. 

 Lister, pi. 544. f. SO, and 31 Montagu, pi. 13. f. 9. 

 Patella Mitrula. Dorset Cat. pi. 22. f. 7. a. 



Shell thick, strong, nearly opake, 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. 



YVey mouth, and the south of Ireland : rare. v. m. 



13. Patella 



