158 PALEONTOLOGY OF NEW JERSEY. 



SO, and about three-fourths as high as long. Beaks small, appressed, situ- 

 ated behind the anterior third of the length; a slight umbonal angulation 

 marks the posterior slope, between which and the cardinal margin the sur- 

 face of the shell is flattened, corresponding to the truncation of the posterior 

 end of the shell. Surface of the shell marked by somewhat regular con- 

 centric striae, which are abruptly bent at the umbonal ridge and pass direct 

 nearly to the cardinal margin. 



I have seen several imperfect examples of the casts of this shell from 

 New Jersey, but no perfect ones. The species attains a rather large size, 

 Mr. Conrad's example of the species being more than three and three-fourths 

 inches long by two and a half inches high. No examples which I have seen 

 furnish any evidence of the hinge characters, but the general expression of 

 the partial casts is much like that of a species of Dosinia, from which genus 

 the distinct inequality and twisting of the valves would serve to distinguish 

 it. Mr. Conrad states in his description that the right valve is convex and 

 the left one flat. In the specimen which he used and figured, and which is 

 now before me, the left valve is about half as convex as the right one, and 

 both are decidedly bent or twisted near the posterior end, as are those of 

 many of the divisions of the TeUinidce. In the general expression of the 

 cast there is no feature to distinguish it from a cast of a large Sanguinolaria. 



The species differs from those which I have referred to C. excavata, 

 Morton's sp., in the less inequality of the valves, and more decidedly so in 

 the marked truncation of the posterior extremity at right angles to the axis 

 of the shell; also in the angulation of the umbonal ridge, as well as in being 

 much more transverse. 



Formation and locality, — In the Lower Marls at Holmdel, New Jersey, 

 in collections obtained from the Rev. Dr. Riley, and from Burlington, New 

 Jersey, as marked on the specimen originally used by Mr. Conrad. I have 

 also seen specimens which, judging from the lithological characters, must 

 have come from several difi'erent localities, but which were not indicated. 



