LAMELLIBRANCHIATA OF THE LOWER MARLS. 153 



Suborder SINUOPALLIATA. 

 VENERID^. 



Genns CALLISTA Poli. 



Callista Delawarensis. 



Plate XXII, Figs. 8-10. 



Dione Delmmrensis Gabb. J. A. N. S., Phil., 2d ser., Vol. IV, p. 302, PI. XL VIII, Fig. 18. 



Callista Belawarensia Gabb. Synop., p. 105. 



Dione Delawarensis (Gabb) Meek. Smithson. Check-list, p. 13. Stoliczka, Pal. Iiidica, 



Vol. Ill, 1G5. 

 Comp. Venus Bipleyana Gabb. J. A. N. S., new ser.. Vol. IV, p. 393, PI. LXVIII, Fig. 22. 

 Not Garyates Delaicarensis (Gabb) Conrad. Am. Jour. Conch., Vol. V, p. 41, PI. I, Fig. 6. 



Shell of moderate size, slightly transverse, with the beaks anterior to 

 the middle, small and but little incurved. Outline ovate, broadest oppo- 

 site the beaks and somewhat pointed posteriorly. On the casts the teeth 

 are small, the muscular imprints rather large and moderately distinct, and 

 thepallial line deeply and rather broadly sinuate; the sinus rounded at the 

 extremity and directed forward and upward. Only small shells preserving 

 the substance have been observed. They have the same general form with 

 the casts, while the surface is marked by very regular, gradually increasing, 

 concentric ridges parallel to the margin, and are flattened on the surfaces 

 and separated by deep, sharp, but narrow grooves. 



The cast of this species are not easily distinguished from those of one 

 or two other species, and especially from casts from the Eocene sands of the 

 upper marl beds at Farmingdale, N. J. It may be said to differ in that one 

 being longer in front than behind the beaks, and from what evidence can 

 be obtained from the casts, also in the surface characters, as that one appears 

 to have been marked only by fine concentric lines of growth instead of 

 the regular ridges of this one. From C. veta, Conrad, it differs in being a 

 larger shell and proportionally less ventricose, as seen in the casts. From 

 some of the Eocene casts I cannot see distinguishing features. I see no 



