PATELLA. LIMPET. Ill 



16. Patella Fissura. Silt Limpet. 



Lister, pi. 543. f. 28 Pennant, pi. 93. f. 3 Da Costa, 

 pi. 1. f. 4 Donovan, pi. 3. 2 Dorset Cat. pL23. f. 4. 



Shell oblong, conic, brown or white, semitransparent, 

 with strong regular longitudinal ribs and transverse ones 

 in the interstices, toothed round the margin, where on one 

 side is a narrow fissure or slit which sometimes reaches 

 nearly halfway up the shell : crown nearly central, pointed 

 and curved inwards, but hardly forming a single volution : 

 length of the base half an inch j breadth and height about 

 half as much. 



On most sandy coasts, v. v. 



C. With the crown perforated, 17 to 20. 



17. Patella Apertura. Open Limpet. 



Montagu, pi. 13. f. 10. 



Shell oblong-oval, flatfish, semitransparent, white with 

 a few longitudinal brown streaks reaching half way up from 

 the margin, with strong longitudinal tubercled ribs crossed 

 by a few circular ridges : crown recurved, the point small 

 and turning inwards so as occasionally to form a single vo- 

 lution which is attached to the shell, and just below the 

 commencement of the volution is a rhombic perforation ; 

 inside smooth glossy, with the circumference oval, and 

 toothed at the edge by the ribs : length nearly a quarter 

 of an inch ; height not half as much. 



On the western coasts : very rare. v. m. 



18. Patella Grasca. Cancelled Limpet. Fig. 82. 



Lister, pi. 527. f. 2 Pennant, pi. 92. f. 3 -Da Costa, 

 pi. 1 . f. 3 Dorset Cat. pi. 23. f. 3. 



Patella reticulata, Donovan, pi. 21. f. 3. 



Shell thick, opake, oblong-oval, very little conic, white 

 or dull brown, with strong longitudinal ribs of unequal 

 size, crossed by transverse ones, giving a rather tubercled 

 appearance to some of them : crown not much elevated, 

 placed nearer to one end, truncate, and furnished with an 

 oblong perforation ; inside smooth, white, sometimes 

 marked with brown or dull purple rays j the margin a little 



indented, 



