213 
or teeth, at the base of the emarginated ear extending from near 
the apex to a point beyond the ear. 
Many of the MoUusca 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 efforts, 
succeeded in leaping from their prison. No sooner did they fall 
upon the water, than by striking their valves rapidly together, 
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 bas- 
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 V’ We have 
not learned that this remarkable flotilla has been observed since 
the time of Pliny. 
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’Herbigny says that in Italy they are called cape 
sante, in Holland mantels ; in Languedoc coquilles large, in Brit- 
tany and Lower Normandy, Koficlies. Beshayes enumerates 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, Muller. Chem. and Mart. Conch, vol. 7, 
314 and 318, Q^,fig. 615 and 616. Gmel Lam. an. sans vert, 
p. 474. Desh. Encycl. Meth.p. pi. 212^, fig. 1. 
