PATELLA. 1041 



patelliformis, to which he has compared it, in describing 

 that species in the Fauna Suecica. 



PERVERSA. bQ. Shell membranaceous, brittle, and 

 very smooth, with the summit )3ointed and 

 recurved ; base roundish-oblong. 



Patella perversa. GmeHn, p. 3714. 

 Patella, No. 39- Schroeter Eitil. ii. p. 457. 

 Le Liri. Adanson Senegal, p. 32. t. 2. f. 2. 

 Martini, i. p. 148. 1. 12. f . 1 14, A and B. 



Inhabits the coasts of the Cape de Verd, Goree, and Magdalen 

 Islands, on rocks. Adanson. 



This, though a marine species, appears from Adanson's account 

 to be very nearly allied to those which inhabit fresh water : 

 he says, that the summit is placed nearest to that end of the 

 shell which covers the tail of the animal, and that it is re- 

 curved in the same direction ; it is coated with an epidermis, 

 which gives the shell a rust-colour ; the base is about four 

 lines long and three broad. 



LACUSTRis. 57. Shell membranaceous, brittle, with 

 the summit pointed and reflected ; base 

 oval. 



Patella lacustris. Litinaus St/st. Nat. p. 1260. Schroetet 

 Fluss. p. 203. t. 5. f. 1, 2, and 3 ; and Einl. ii. p. 421. 

 Lightfoot in Phil. Trans. Ixxvi. p. 168. t. 3. f. 4. Pen- 

 nant ZooL iv. p. 143. Donovan, v. 1. 147. Maton and 

 Racket, in Lin. Trans, viii. p. 232. Dorset Cat. p. 58. 

 t. 22. f. 8. 

 Patella fluviatilis. Da Costa Brit. Conch, p. 1. t. 2. f. 8. 



Gmelin, p. 37 1 1 . Montagu Test. p. 482. 

 Ancylus fluviatilis. Midler Verm. ii. p. 201. 

 L'Ancille. Geoffroi/, yt. V24. t.3. 



Lister Anim. Ang. t. 2. f. 32, and Conch, t. 141. f. 39. 

 Gualter, t. 4. f. BB. Argenville, t. 27. f. 1. 

 Inhabits most of the rivers and lakes in Europe. Da Costa. 

 The base is about three-eighths of an inch long, and two- 

 eighths broad ; the shell is thin, brittle, and transparent, of a 

 whitish horn-coloui", usually coated with a dark brown or 

 greenish epidermis, and slightly wrinkled transversely. Da 

 Costa, though he changed the name, was aware that this is 

 the Linnaean P. lacustris. Montagu says, *' a Variety is 

 sometimes met with, finely striated longitudinally from the 

 beak, and we received some specimens, from a fresh-water 



