1903.] NATURAL SCIENCES OF PHILADELPHIA. 261 



NOTES ON THE CONRAD COLLECTION OF VICKSBURG FOSSILS, 

 WITH DESCRIPTIONS OF NEW SPECIES. 



BY THOMAS L. CASEY. 



The following paper anticipates a more elaborate descriptive cata- 

 logue of the Vicksburg fossils which the author has in view, and it is 

 intended that the species here described as new shall be figured with 

 the others when that is published. It will be sufficient to state that 

 nearly all the species here named for the first time are well known, and 

 represented in every collection from Vicksburg, Red Bluff or Jackson, 

 that can be considered in any wa}'' complete, and there can be but little 

 doubt of their ready identification from the diagnoses, comparative 

 or otherwise, which it is thought are drawn up with sufficient fullness 

 and accuracy for that purpose. 



PELECYPODA. 

 Corbula laqueata u- sp. 



C. filosa Con. (Am. Jour. Cone, I, p. 145; nomen prseoc). 



Differs from the species named perdvbia by De Gregorio; at least 

 on comparing Vicksburg specimens witli those from Red Bluff, I find 

 that the latter form is shorter and differs greatly in sculpture in the 

 umbonal region. The true rugse do not begin for a considerable dis- 

 tance from the beak in the Red Bluff form, this region being smooth 

 or feebly wrinkled, whereas in the Vicksburg species the rugae begin 

 very near the beaks, and the latter are more strongly gyrate. As the 

 Vicksburg species is distinct I would propose the name given to it in 

 manuscript by Conrad. C. laqueata is a small species, never materi- 

 ally exceeding 6 mm. in length by 5 in height, the posterior flattened 

 surface feebly delimited, the bounding line being rounded and not cari- 

 nate ; the rugse are comparatively coarse ventrally. It is confined to 

 the upper marl and represented in the lower limestone by a variety 

 having much finer rugae. 



The type of Corbula interstriata appears to be the only known repre- 

 sentative of the species, and I have never been able to discover it at 

 Vicksburg. I did not examine the hinge with much care, but the 

 general appearance of the species is not very unlike that of C. gibbosa 



