30 AMERICAN JOURNAL 



A single specimen, still imbedded in the mould of its nest, 

 from the same rock as the Volutilithes and Thracia. 



RJ5TA, Gray. 

 R. GIBBOSA, Gabb. 



Shell large, thin, gibbous, broadly ovate; anterior end broadly 

 and about equally rounded ; posterior end narrowly and com- 

 pressedly beaked ; beaks central, small, incurved ; cardinal mar- 

 gin sloping down about equally on both sides ; base broadly and 

 regularly convex. Surface ornamented by irregular concentric 

 folds. 



Length 3 inches, width from beak to base 2-5 in., diameter 

 1*6 in. 



From a compact yellowish clay-stone, associated with Voluti- 

 lithes, &c. 



Closely allied to R. canaliculata, Say, from the coast of South 

 Carolina, but more equilateral, less produced in advance, the 

 greatest prominence of the posterior end placed higher (or 

 nearer the beaks) and the bases more prominently convex. The 

 surface plications are also finer and more numerous. 



STRIGILLA, Turton. 



S. PRORA, Hanley, sp. 



Tellina prora, Hanley, Zool. Proc. 1844. 



id. Hanley, Thes. Conch, p. 243, pi. 60, fig. 152. 



T. [Peronceoderma) i^rora^ H. and A. Adams, Gen. Rec. Moll, 

 p. 396. 



A single specimen, apparently from the same rock as the 

 Amindlina, 



CARDIUM, Linn. 

 8. Gren. Ljevicardium, Swains. 



C. (L.) PERTENUE, Gabb. 



Shell very thin, gibbous, somewhat inequilateral, most pro- 

 duced posteriorly ; beaks small, strongly incurved ; cardinal 

 margins equally and regularly sloping ; base broadly rounded, 

 continuously to the middle of the anterior end, where the curve 

 joins the nearly straight slope from above, with a narrow angle ; 

 posterior end apparently considerably produced (from the lines 

 of growth, the lower part being broken). Surface very smooth, 

 only marked by minute lines of growth. 



Length (broken) 1-8 in., total length apparently 2 in., width 

 from beak to base 1*75 in., diameter 1"45 in. 



