156 PALEONTOLOGY. 



margin narrower, and rather abruptly rounded, or sometimes apparently 

 slightly truncated, being most prominent below; basal margin forming a semi- 

 elliptic or semi-ovate curve, being sometimes more prominent anteriorly ; dor- 

 sal outline sloping from the beaks toward the extremities; beaks moderately 

 prominent, very nearly central, and incurved with little obliquity; umbonal 

 slopes merely rounded, and not terminating in a flexure of the posterior basal 

 margin. Surface apparently merely marked with fine, obscure, irregular 

 lines of growth. Hinge merely known to possess linear anterior and posterior 

 lateral teeth. Ligament and internal characters unknown. 



Length, L35 inches; height, 0.90 inch; convexity, about 0.50 inch. 



The specimens of this shell in the collection agree so nearly with a form 

 described by the writer in connection with Dr. Hayden, from the Upper 

 Cretaceous beds on Deer Creek near the North Platte, under the name Tel- 

 Una nitidula, that I was at one time inclined to think they might belong to a 

 variety of that species. Still, as they are merely internal casts, giving but a 

 limited knowledge of the hinge, and showing nothing of the internal jchar- 

 acters, it is much more probable that they are really very distinct. So far 

 as 'regards their form and general appearance, they seem only to difi"er in 

 •having the anterior side rather more produced and sometimes wider. 



From this general resemblance, however, I have, in the absence of any 

 knowledge of the nature of its cardinal teeth or pallial line, ventured to 

 refer it provisionally to the same section of the Mactra group to which 

 Tellina nitidula is now believed to belong; that is, to Cymbophora, Gabb. 

 I should have been inclined to refer it to Macoma or Gastrana, were it not 

 for the impressions of lateral teeth seen before and behind the beaks in the 

 casts. 



Locality and position. — Whitish Cretaceous sandstone, East Caiion Creek, 

 Wasatch Range, and near Coalville, Utah. 



TELLINID^. 



Genus TELLINA, Linnaeus. 

 Tellina ??isoNEMA, Meek. 



Plate 15, fig. 6. 



Shell transverse, elliptic-subtrigonal in outline, compressed, and nearly 



