213 



or teeth, at the base of the emarginated ear extending from near 

 the apex to a point beyond the ear. 



Many of the Mollusca are fixed during life to one spot, others 

 glide along with a slow and regular snail-like movement ; but loco- 

 motion in this genus is rapid, and by a succession of springs or 

 leaps. An alternate motion of opening and quickly and forceably 

 closing the valves, enables them to rise to the surface, and they 

 sometimes make small leaps above it in ricochet. When left upon 

 the beach by the recession of the tide, they regain the water by 

 the same action. Mr. Lesson immersed a basket of Pectens in the 

 water of the sea, within about six inches of its rim. The individu- 

 als, he says, which formed the superior layer, constrained in their 

 movements by those that were beneath, after many fruitless efi"orts, 

 succeeded in leaping from their prison. No sooner did they fall 

 upon the water, than by striking their valves rapidly togethei, 

 they ran or rather skipped a few seconds upon the surface and 

 then sunk to the bottom. In this way all the contents of the ba:?- 

 ket disappeared within fifteen minutes. Smellie repeats from Pliny 

 that " when the sea is calm, troops, or little fleets of Scallops, are 

 often observed swimming on the surface. They raise one valve of 

 their shell above the surface, which becomes a kind of sail, while 

 the other remains under the water, and answers the purpose of an 

 anchor, by steadying the animal and preventing its being overset. 

 When an enemy approaches, they instantly shut their shells, 

 plunge to the bottom, and the whole fleet disappears !" We have 

 not learned that this remarkable flotilla has been observed since 

 the time of Plin}^ 



Many of the species are esteemed as food and are exposed for 

 sale in the markets. They are commonly known by the name of 

 Scallop, and the English collectors call them Fans in allusion to 

 their form. D'llerbigny says that in Italy they are called ca/>f 

 sante, in Holland mantels ; in Languedoc coquilles lar^e, in Brit- 

 tany and Lower Normandy, Kofiches. Deshayes enumerate," two 

 hundred species, more of which are fossil than living. 



Pecten islandicus. — Specific character. Shell suborbicular, 

 with numerous rays; orange or rufous, with darker concentric 

 bands. 



Ostrea islandica, Mvller. Chem. and Mart. Conch, vol. 7, p. 

 314 and SIS, pi. 6b, Jig. 615 and 616. Gmel Lam. an. sans vert. 

 p. 471. Desh. Encycl Meth. p. 12^, pi 2\2>,fig. 1. 



