114 THE NAUTILUS. 



other edible species of mollusca, such as clams, quohogs, mussels and 

 oysters, but only the large muscle in the centre which holds the 

 valves together; this muscle in adult pectens is about an inch in 

 diameter and the same in length. The shells are subject to great 

 variety in color, sometimes having one valve pure white and the 

 other yellow, red, purple, or mottled and banded with several colors, 

 when young ; the adult shells generally lose their brilliant shades 

 and become of a uniform slate tint, with one valve, however, always 

 lighter than the other. The young shells frequent the shore and are 

 very active ; I have often put out my hand to take one, when just as 

 I almost had it, it would suddenly shut its valves and skip away out 

 of reach. At times I have seen them at Apponang so abundant that 

 they were piled up in layers six or eight inches deep, and at other 

 times not one could be seen. The adults inhabit deeper waters and 

 are dredged from the bottom from boats. 



209. Pec ten tenuicostatus Migh. and Ad. 



Syn.: Pecten magellanicus Con., Gld., Stimp, DeKay. 



Shell large, round, inequivalve, lower one nearly flat, upper one 

 convex, ears nearly equal ; surface with fine radiating, punctured 

 lines; lower valve white; upper valve brownish-red, dingy; interior 

 white, glossy and smooth, with a different set of radiating lines from 

 those on the exterior. Length five inches, height five and a half, 

 breadth one and a half. 



This is a northern species, found of large size on the coast of 

 Maine and everywhere north of Cape Cod ; smaller ones are obtained 

 from the stomachs of fishes. It inhabits deep water off Block Island, 

 and in southerly storms is driven up in large numbers on the shore 

 at Point Judith. 



Family Anomiidse. 



Shells thin, pearly, with a notch or hole through the right or 

 lower valve near the beaks, to which is attached a plug, closing the 

 orifice and also serves to attach the shell to other objects. There are 

 two genera, Placunanomia and Anomia, divided into several sub- 

 genera. 



Genus Anomia, Linne., 1767. 



The animal of Anomia differs from Ostrea in having a small foot, 

 one of the peculiar characteristics of oysters being the entire absence 

 of any foot. 



