314 



POPULAR CONCHOLOGY. 



Pecten. Midler. — Shell regular, nearly round, eared, 

 ribbed, or furrowed, nearly equila- 

 teral, inequivalve ; ligament internal, 

 inserted into a triangular groove ; 

 hinge margin straight ; no teeth ; 

 bosses contiguous. Animal ^ shaped 

 as the shell, mantle freely open, with 

 pendent margins bearing (usually 

 two) fringes of tentacular filaments, 

 the one series at their fixed, the 

 other at their free border ; among 



° Pecten varvus. 



the former are ranged globular 



shining ocelli ; no siphonal tubes ; body large, apiculate ; 

 foot small, cylindrical, with a byssal groove, from whence 

 a weak byssus is spun, mostly when the animal is young ; 

 mouth surrounded by foliaceous leaflets, and two pair of 

 labial tentacles, which are smooth externally, pectinated 

 internally ; branchial leaflets equal, each pair partially 

 doubled on itself.* — 176 species f ; also fossil. 



The animal of the Pecten has the power of making fre- 

 quent and sudden contractions of its muscles, by which 

 means it moves rapidly through the water ; and it requires 

 some agility to catch the shell, as it flutters amongst the 

 corals where it dwells. Aristotle mentions their power of 

 leaping, and this observation has since been confirmed. 

 A basket, full of the common Pecten placed at the edge of 

 the water has been spedily emptied, by the individuals 

 springing from their confinement to their native element. 

 M. Lesson immersed a basket of Pectens in the sea, the 

 water coming to within six inches of its rim. The indivi- 

 duals, he says, which formed the superior layer, constrained 

 in their movements by those that were beneath, after 



* Forbes' s British Moll. 



f Reeve's Iconica. 



