136 



CHAPTER XXXV. 



OF THE PATELLA. GENUS XXXII. 



PATELLA. 



"Animal a Limax. Shell univalve, somewhat conic, without a spire." — 



Linn. 



LiNNiEUs makes five divisions of this genus : 



1st, Labiatee, 4th, Integerrimce, 



2nd, Dentatce, And Bth, Perforaice. 



3d, Mucronateey 

 Of these the first and last are easily distinguished firom the 

 others ; but the shells of the second, third, and fourth vary 

 by such almost imperceptible degrees, that it is nearly if not 

 quite impossible to know where to draw the line of distinc- 

 tion. 



This genus is perhaps as well defined, and as perfectly distinct 

 from the rest, as any one of the whole number, though consist- 

 ing of a great variety of species ; therefore it appears unneces- 

 sary to divide it into many, as Lamarck has done : they are 

 all very open shells, not inclosing the animal, but covering 

 the back only : many species are nearly conic, as giceca ; in 

 some the point is flattened, the back being more or less rounded, 

 but with a somewhat oval mouth, as compressa : others are 

 nearly flat ; some have the tip or apex near the centre, as 



