Maryland (Jeological Survey 659 



Genus CYPRICARDINIA Hall 



Cypiucaudixia ele(.axs n. >p. 



Plate LXVI, Fig. SI 



Description. — SIk'11 of medium size, siibrhomboidal elongate; ventral 

 margin nearly straiglit, sliglitlv sinnate posterior to middle. Posterior 

 extremity oI)li<nicIy innicate, abrii])tly rounded l)elow; cardinal margin 

 nearly straiglit ; anterior end projecting slightly, I'mmded below. Valves 

 quite convex near umbo; unil)onal slope prominent, I'ounded, with a 

 conspicuous sinus anterior to it. Surface marked by eoneentric, sub- 

 equally distant lainellose undidalions, between which are tine concentric 

 strias. 



Length 37 nmi. ; height 15 mm.; thickness 11 mm. 



The generic relations of this species are not fully determined, the 

 exterior of one valve only having been observed. The ornamentation is 

 that of the genus Ci/pricdrdinia. The interior of a variety of this species 

 is, however, known. This species closely resembles (7. iiideniafa of the 

 Onondaga and Hamilton of New York. It differs from that species in 

 shape, not being ovate, the posterior end being little wider than the anter- 

 ior end at umbo, while tlie hinge-line is shorter. It also differs in orna- 

 mentation. It resembles species of GouiopJiora but the umbonal slope 

 is not so angular as in that genus, while the ornamentation is that of the 

 genus to which it is referred. 



Occurrence. — Jennings Form.vtiox, Chemung ]\Iejiber. Bellegrove^ 

 300 feet west of schoolhouse. 



Collection. — Maryland Greological Survey. 



Cypricabdinia elegans var. angusta n. var. 



Plate LXVI, Figs. 23-24 



Description. — This variety differs from the typical form in having a 

 much more angular umbonal slope and in being proportionally somewhat 

 higher. The cast of the interior shows distinct scars for attachment of 

 the anterior adductor muscles and small scars above and posterior to them,. 



