MOLLUSCA. 563 



Description. — "Shell small, triangularly ovate, very transverse, 

 -with very sharp, pointed, and recurved beaks, situated just within 

 the middle third of the length of the shell and nearest to- tlie 

 anterior end. Valves flat, marked by fine concentric lines of 

 growth and a few (three or four) broad, oblique undulations of 

 the surface which pass from the posterior hinge-line forward to 

 the basal margin. There are also a few obliquely concentric 

 wrinkles on the antero-cardinal margin which extend only a short 

 ■distance over the disk of the valve. Along the position of the 

 posterior umbonal ridge, the surface striae are abruptly deflected 

 -upward, marking the position of the ridge and defining the pos- 

 terior slope O'f the valve. Posterior end of the valve narrow 

 and truncate ; anterior end obtusely angular ; basal margin regu- 

 larly and broadly arcuate. Inner margin of the valves crenulate; 

 muscular scars small and faintly marked." (Wliitfield.) 



Reworks. — This species has previously been known from but 

 a single locality, Haddonfield, New Jersey. It is now recognized 

 in two other localities, at Lorillard in the Woodbury clay, the 

 same horizon as the Haddonfield specimens, and at a locality near 

 Marlboro in the Wenonah sand. The Lorillard specimens are, 

 for the most part, fragmentary, but they are usually larger than 

 those from Haddonfield, one specimen having a length of 25 mm., 

 and the broad, oblique undulations are more conspicuous. The 

 Marlboro specimens do not grow larger than those from Haddon- 

 field and seem to lack entirely the oblique undulations. 



Formation and locality. — Woodbury clay, Haddonfield (183), 

 and Lorillard (102); Wenonah sand, near Marlboro (130). 



Geographic distribution. — New Jersey. 



Super-family CYRENACEA. 

 Family OYBBNIDAE. 



Genus CoRBicuivA Megerle. 



Corbicula annosa (Conrad). 



Plate LXIL, Figs. 1-3. 



1869. Astarte annosa Con., Am. Jour. Conch., vol. 4, p. 279, 

 pi. 20, fig. 5. 



