152 PALEONTOLOGY. 



umbonal slopes and back part of beaks angular, the angularity being con- 

 tinued obliquely to the posterior basal margin, while the surface behind 

 these angular slopes is flattened, and rather abruptly inflected to the trun- 

 cated hinder margin. Surface ornamented by distinct radiating non-spinif- 

 erous costse, about equal to the intermediate furrows; costse largest and 

 sometimes bifurcating on the flattened surface behind the umbonal angles, 

 and simple and very regular in front of the same, where they gradually 

 diminish in size anteriorly; lines of growth moderately distinct. 



Length, about 0.80 inch; height, 0.75 inch; convexity, about 0.60 inch. 



The specimens of this shell in the collection seem to agree pretty closely 

 with C. curtum, but are proportionally slightly longer, with rather more 

 depressed beaks, and less sloping anterior and posterior dorsal margins. 

 Hence, I am not quite sure of their exact specific identity. At the time this 

 report was originally prepared, I supposed the smaller shell, represented by 

 fig. 3 a of the same plate, might possibly be the young of that here under 

 consideration; but, on subsequently collecting and examining a number of 

 specimens at the same district and horizon, I was led to believe these forms 

 much more probably distinct, and consequently proposed the name C. suh- 

 curtum for that represented by our fig. 3 a, in one of Dr. Hayden's reports. 



These shells belong to the genus Cardium, but not to the typical sec- 

 tion. I originally referred the typical C. curtum very doubtfully to the 

 section Hemicardium ; but it cannot be properly included in that section, 

 being much nearer the subgenus Fragrum, but still not agreeing with that 

 group either. 



Locality and position. — The type-specimens of C. curtum were brought 

 by Captain Raynolds from Gros Ventres River, Wyoming, from a gray 

 sandstone of Cretaceous age. The specimens here under consideration came 

 from Chalk Creek, two miles west of Uptown, Utah, where they occur in a 

 whitish Cretaceous sandstone. 



Caedium subcurtum. Meek. 



Plate 15, fig. 3 a (not fig. 3). 



Cardium s'&hcurtum, Meek (1873), see foot note in Dr. Hayden's Sixth Ann. Eeport Geol. 

 Survey of the Territories, 476. 



Shell under medium size, truncato-suborbicular, about as high as wide. 



