FAMILY 4. PECTINACEA. 153 



erby, Genera of Shells, No. 14. De Blainville, Manuel de Malaco- 



logie, pi. 65 bis, f. 7. 

 Mytilus margaritiferus, Linnaeus. 

 Meleagrina margaritifera, Lamarck. 

 Margarita sinensis, Leach. 



Family 4. PECTINACEA. 



Testa vel libera vel affixa, ssepe inaequivalvis, subirregularis, plerumque ad 

 basem utrinque auriculata. Ligamentum internum aut semi-inter- 

 num, in fossula centrali insertum. Animal raro bysso affixum. 



The Pectinacea are an interesting and beautiful family of mollusks ; 

 their shells, especially those of the genera Pecten and Spondylus, exhibit 

 a most lively display of colours, and have long been highly valued by 

 collectors. They were originally included by Lamarck in his family of 

 ' Les Ostracees,' but he subsequently separated them under the title of 

 ' Les Pectinides,' on account of the shell being generally auriculated at 

 the base, with the valves radiated like a comb. De Blainville's family of 

 the Subostracea is precisely the same ; in fact, Lamarck's distribution of 

 the genera has been for the most part adopted by succeeding naturalists. 

 We have still, however, a very considerable range of characters through- 

 out the family of the Pectinacea : in the genus Pedum, for example, the 

 animal attaches itself by a byssus, passing out, as in Perna, through a 

 notch on one side of the hinge ; and the shell is moreover strongly 

 characterized by the dorsal area which the valves form as they advance 

 in growth. Now, in the genus Pecten, this area or disc entirely disap- 

 pears ; the byssus is said to be very small, and the shell does not become 

 attached, except in one single instance; this species too has been separated 

 on that account as a distinct genus {Hinnites), and probably ought to 

 remain so. In the genera immediately following, Plicatula and Spondylus, 

 there is a new change of character in the appearance of strong cardinal 

 teeth, and the dorsal area or disc is again very remarkable. When we 



vol. i. x 



