INVEETEBEATB PALEONTOLOGY. 171) 



,°>. macrocallista, Meek. 



Shell transversely elongate-oval, with surface smooth ; pallial 

 sinus and hinge nearly typical, excepting that the sublunular or 

 anterior lateral tooth is generally more compressed, more oblique, and 

 more remote from the cardinal, and the posterior lateral much more 

 elongated, and nearly horizontal. — Venus gigautea, Gmelin. 



4. pitar, Roem. (=z Caryatis, Roemer). 



Shell nearly typical in form and dentition, excepting that the 

 valves are sometimes more convex, and the anterior lateral or sub- 

 lunular tooth always subcorneal in the left valve; pallial sinus deep, 

 and more or less obtusely subtrigonal ; surface concentrically 

 striated. — Venus lumens, Gmelin. 



5. aphrodina Conrad. 



Shell with form, surface, and pallial line as in the last, but with 

 anterior cardinal tooth of left valve thicker, and the anterior lateral or 

 sublunular tooth much more compressed from above and below, 

 rugose or granular instead of smooth, and elongated parallel to the 

 anterior dorsal margin, instead of nearly conical. — Meretrix Tippana, 

 Conrad. 



? 6. dosiniopsis, Conrad. 



Shell suborbicular, or transversely ovatc-subtrigonal ; with surface 

 only concentrically striated ; hinge broad and strong, with anterior 

 lateral or lunular tooth sometimes rugose, distinct from the cardinal, 

 and somewhat extended parallel to the margin above ; cardinal plate* 

 continued broad posteriorly, and provided with an obscure, remote, 

 posterior lateral tooth in one or both valves ; pallial sinus rather deep, 

 triangular, and ascending.— D. Meekii, Conrad. 



It is not without some hesitation and doubt that I have concluded to 

 place the last of the above-named groups as a section of Callista In its 

 rounded outline, broad hinge, and rather well-developed posterior lateral 

 teeth, and elongated rugose anterior lateral, it contrasts strongly with tin; 

 more typical species of the genus ; but it seems to agree so nearly with some 

 of the types that appear to fall into this genus, that I have concluded to range 

 it provisionally as a marked section of the same. I should remark here, 



