CONCHIFERA. 



257 



don double, obscure ; pedal impression only in the left valve, or obsolete 



:% ITS). 



Animal with the mantle quite open, its margins double, the inner pen- 

 lent like a curtain (m) finely fringed; 

 it its base a row of conspicuous round 

 )lack eyes (ocelli) surrounded by 

 :entacular filaments; gills (/br) ex- 

 ceedingly delicate, crescent-shaped, 

 [uite disconnected posteriorly having "' 

 ;eparate excurrent canals ; lips foli- 

 iceous ; palpi truncated, plain out- 

 >ide, striated within ; foot finger-like, 

 grooved, byssiferous in the young. JFig. 179. Pecten varius.* 



The Scallop (P. maximus] and " quin" (P. opercularis) are esteemed 

 lelicacies ; the latter covers extensive banks, especially on the N. and W. of 

 Ireland, in 15 to 25 fin. water. The scallop ranges from 3 40 fms. : its 

 body is bright orange, or scarlet, the mantle fawn-colour, marbled with 

 )rown ; the shell is used for " scalloping" oysters, formerly it was employed 

 is a drinking cup, and celebrated as such in Ossian's " hall of shells." An 

 illied species has received the name of " St. James's shell" (P. Jacoboeus) ; 

 t was worn by pilgrims to the Holy -land, and became the badge of several 

 Drders of kmghthood.f 



Most of the Pectens spin a byssus when young, and some, like P. varius, 

 o so habitually ; P. niveus moors itself to the fronds of the tangle (La- 

 ninaria.} 



The Rev. D. Landsborough observed the fry of P. opercularis, when less 

 tian the size of a sixpence, swimming in a pool of sea- water left by the ebbing 

 f the tide. "Their motion was rapid and zig-zag; they seemed, by the 

 udden opening and closing of their valves, to have the power of darting like 

 n arrow through the water. One jerk carried them some yards, and then 

 y another sudden jerk they were off in a moment on a different tack." 



The shell of Pecten and the succeeding genera consists almost exclusively 

 f membranous laminse, coarsely or finely corrugated. It is composed of 

 wo very distinct layers, differing in colour (and also in texture and destruc- 

 ibility), but having essentially the same structure. Traces of cellularity 

 re sometimes discoverable on the external surface ; P. nolilis has a distinct 

 rismatic-cellular layer externally. (Carpenter.} 



