134 PALEONTOLOGY OF NEW JERSEY. 



the posterior side very slightly straightened, and the hinge-margin only 

 slightly arcuate. Umbones slightly gibbous, with the posterior umbonal 

 slope just perceptibly more abrupt than the anterior side and of about 

 equal width. Surface of the cast marked near the border of the valves by 

 moderately strong crenulations, of which about six may be counted in the 

 space of a fourth of an inch on the basal margin of the specimen figured. 

 The cast as compared with that referred to C. muUiradiatum Gabb is less 

 ventricose, with less abrupt postero-cardinal slopes, smaller and less elevated 

 beaks, and a proportionally broader and less arcuate hinge-border; and 

 the indications of striae on the surface somewhat coarser. The surface of 

 the shell which I have supposed to belong to this species, both from the 

 form of the shell as indicated by the cast and in the matrix from which the 

 surface is obtained, and from indications of the ribs on the posterior side of 

 the cast figured, has been covered by radiating ribs, which are smooth and 

 flattened on the surface, and are characterized by rows of short spines or 

 granules in the depressions between; every third depression bearing spines, 

 and the two intermediate ones having granules only on the body of the 

 shell, with sometimes a single row only between the rows of spines on the 

 sides of the valves. The spines are only moderately long, and appear to 

 have been slightly recurved and laterally compressed, while the granules 

 are rounder and arranged more closely, there being from three to six in the 

 distance between the spines. This character of surface is very distinctive 

 as compared with that referred to C, muUiradiatum^ where every rib has 

 its spines, though mostly arranged on the sides instead of exactly in the 

 depression, as in this case. I cannot find that any figure has been given of 

 the species by the author, but from the nature of his reference to the form 

 of C. muUiradiatum in his description, cannot doubt the correctness of the 

 reference here made.^ 



Formation and locality, — The specimens on which I have founded this 

 species are marked as from near Burlington, New Jersey, and are in the 



* Subsequently I obtained from the collection of the Academy of Natural Sciences at Philadelphia 

 specimens preserving the shell, marked ''Haddonfield, N. J./^ on which the character of the surface as 

 described above is clearly shown. One of these is labeled Cardium dumosum Conrad, subgenus Cai'dea, 

 and the other C. {Track.) AlabamiensiSj Gabb. The former in Mr. Conrad's handwriting, and the latter 

 in Mr. Gabb's, so far as I can determine. They are, however, both the same species, and both individ- 

 uals, are figured on one plate. 



