MUSSELS AND PECTENS 



43 



water at various stations extending from Bering Sea 

 to Mexico. The shell is thin, glossy, and unsculp- 

 tured, translucent white in color, and measures about 

 an inch in diameter. 



Pecten vancouverensis^ Whiteaves, the Vancouver 

 Pecten, is perhaps the smallest member of the genus 

 to be found on our coast. The little shells are only 

 5 mm. across, and are very fragile. Form nearly 

 circular, ribs fine and numerous, color very light 

 brown. It has been collected on the coast of British 

 Columbia, also in San Pedro Bay at a depth of two 

 hundred fathoms. 



Pecten ventricosus, Sby., the Bulged Pecten, is 

 found fossil at San Pedro, and is said to be living 

 from Santa Barbara southward. "P. aequisulcatus 

 resembles this species very closely, but is thinner 

 and flatter and has narrower ribs." (Arnold). 

 Diameter, about two inches. 



We now come to a not- 

 able species which differs 

 from the typical Pectens in 

 that the valves become un- 

 symmetrical when they be- 

 come old. It is called Pec- 

 ten giganteus^ Gray, the 

 Purple-hinged Pecten. It 

 belongs to the division of 



the Pecten genus sometimes 

 known as Hinnites. In its 

 early life it is a true little 

 fan-shell, with thin, fine- 

 ribbed, unequally eared left Fig. 23, x i 



