LIMA. 77 



P. Jacobaus (the famous " pilgrim" scallop) was at 

 one time erroneously supposed to be a native of these 

 seas. It is common in the Mediterranean, and M. 

 Mace has lately included it in a list of shells which he 

 has found at Cherbourg. It is distinguishable from the 

 present species by the ribs of the lower valve being 

 angular instead of rounded. 



Genus II. LI'MA*, Bruguiere. PI. II. f. 2. 



BODY oblong : mantle not furnished with ocelli. 

 SHELL equivalve : cartilage external : muscular scar placed 

 on one side. 



Lima and Pecten have nearly the same characters ; but 

 the value or importance of generic, as well as of spe- 

 cific differences is comparative and varies in each case. 

 In the present genus the animal has a bright uniform 

 colour, while the shell is always white. Both animal 

 and shell in the other genus are more highly favoured 

 in this respect and exhibit various hues. The former 

 has its mantle studded with numerous eyes like the tail 

 of a peacock, and looks down upon its cousin as a poor 

 blind creature. The Lima moves or rather darts through 

 the water like a scallop, but in a contrary posture. The 

 hinder instead of the ventral end is in front, so that the 

 mode of its progression may be compared to that of a 

 fish swimming tail foremost. Some species construct 

 dwelling-places called " nests " out of fragments of 

 shells, nullipores, gravel, and other material, which 

 they ingeniously fasten together by their byssal threads 

 and attach to the roots of large seaweeds. Several 

 young ones often occupy the same nest or case; but 

 when they become adult each individual has a house of 

 * A file. 



