138 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



Glossus (— Isocardia) ; and in doing this it became necessary to use another 

 specific name, cordata having been previously applied to another species of 

 that genus in Europe. 



Since ascertaining, as above stated, that this shell certainly has no 

 lateral teeth, either anterior or posterior, it becomes equally evident that it 

 can no longer be properly retained in the genus Glossus; but I confess that 

 I am still unable to locate it with any degree of confidence in any of the 

 described genera. On the whole, it seems to agree, so far as its characters 

 can be determined from the only specimen yet seen, about as well with 

 Dr. Stoliczka's genus Sphceriola, to which I have provisionally removed it, as 

 with any of the described groups. When specimens can be examined, 

 however, showing the hinge, it is<quite as probable, and perhaps even more 

 so, that it will be found to present different generic characters, and possibly 

 to belong to an undescribed genus. I would be inclined to refer it to 

 Sphcerella, if the muscular impressions were more elongated and the shell 

 thinner. On the other hand, it seems to be about as apt to belong to 

 d'Orbigny's genus Unicardium. 



Locality and position. — Moreau River; from the Fox Hills group of the 

 Upper Missouri Cretaceous series. 



Spliscriola! Warrenana, Meek.* 



Shell globose, rather thick ; anterior and posterior margins regularly 

 and subequally rounded, and each rounding into the more broadly rounded or 

 semicircular base; beaks moderately prominent, gibbous, nearly Central, and 

 incurved, with little obliquity; surface marked by concentric striae : muscular 

 and pallial impressions faintly marked. 



Height and length, each about 1.55 inches ; convexity, 1.42 inches. 



The only specimen of this shell yet found, is, like that of the last, 

 merely an internal cast, with portions of the shell adhering. It gives no 

 idea of the nature of the hinge, beyond the fact that it has no lateral teeth 

 It will be readily distinguished, however, from that shell, specifically, by its 

 less elevated beaks and greater thickness. 



A portion of the left valve, remaining shows a marginal furrow behind the 

 beaks, apparently for a narrow, rather long, external ligament. In regard to its 

 generic affinities, I can only repeat what has been said respecting the rela- 



* Unfortunately, no figure of this species was prepared. 



