FAMILY MYADZ — CORBULA. 241 
lobe on the edge: valves ridged by the stages of growth, convex; beaks moderately prominent, 
Color: epidermis yellowish; beneath white. Length, 1-5 —2+5; width,2-5-—3+*5. Common 
on the Grand Banks: a few valves occasionally found on the shores of Massachusetts. 
GENUS CORBULA. Bruguiéres. 
Animal unknown. Shell moderately solid, subtrigonal, inequivalve, inequilateral, slightly 
gaping. Hinge with a small conic erect recurved tooth in each valve, one received into a 
pit by the side of the other: cartilage between the teeth. Palleal impression feebly exca- 
vated. 
CorRBULA CONTRACTA. 
PLATE XXVIII. FIG. 285. 
(STATE COLLECTION.) 
Corbula contracta. Say, Jour. Acad. Nat, Sciences, Vol. 2, p. 312. 
Cc. id. GonuLp, Invertebrata of Mass. p. 43, fig. 37. 
Description. Shell small, solid, convex; valves subequal, shortest and rounded in front, 
long and pointed behind. Beaks rather prominent, nearly touching each other at their points : 
basal margin contracted and concave in the middle. Surface with regular equidistant con- 
centric impressed lines and intervening ridges. A prominent ridge runs from the beaks on 
each side to the posterior basal margin, including a broad space between them: left valve 
shutting within the other along the basal margin. LEpidermis thin. In one valve the tooth is 
simple, hooked and turned towards the beak ; in the other, it is broader than high, project- 
ing at right angles to the valve, with a deep cavity on the posterior side of the base for the 
reception of the hooked tooth. 
Color. Epidermis dull brown ; beneath dead white. 
Vertical axis, 0°25; transverse ditto, 0°4. Diameter, 0°2. 
This little shell is not uncommon along our coast, from Florida to Cape Cod. I.have 
found it on the shores of Long island, and Mr. Linsley of Stratford has sent it to me from 
the shores of Connecticut. The epidermis is occasionally ferruginous. 
Fauna — Part 6. 31 
