DESCRIPTIONS OF NEW SPECIES. 



ing upward and backward from the uppermost of the longer plications there 

 are several smaller, short ones that end at the postero-dorsal margin. 



Length of the largest example in the collection, sixty -three millimeters; 

 height, thirty-five millimeters. Young examples have very different propor- 

 tions, as well as a marginal outline of different shape. 



This species differs conspicuously from any other fossil Unio known to 

 me, although young examples of it have some resemblance to those of the 

 recent species U. multiplicatus, but the adult specimens have a very different 

 aspect. It differs from U: belliplicatus Meek, from equivalent strata in South- 

 western Wyoming, in its general shape and in the position and distribution 

 of the plications, they being most conspicuous on the anterior portion of 

 that shell, while the corresponding portion of ours is plain. 



Position and locality. Point of Rocks Group; Upper Kanab, Utah. 



Genus CYRENA Lamarck. 

 Subgenus VELOKITINA Meek. 



Cyrena (Vdoritina) erecta (sp. nov.). Shell of medium size, subovate 

 in marginal outline when adult, but subcircular when young, gibbous, espe- 

 cially the upper median portion, but somewhat compressed laterally at the 

 postero-basal portion; front and basal margins regularly and continuously 

 rounded; postero-basal extremity somewhat abruptly rounded upward to 

 the sloping, broadly rounded postero-dorsal margin; umbones elevated; 

 beaks small, incurved, and pointing forward; postero-dorsal margin of each 

 valve flexed strongly inward, so that the hinge-ligament is hidden from 

 sight by side view of the shell. 



Surface marked by the ordinary lines of growth. 



Length, thirty millimeters; height from base to umbones, thirty-four 

 millimeters. 



Position and locality. Salt Wells Group; Upper Kanab, Utah, and Ilil- 

 liard Station, Wyoming. 



Genus TURNUS Gabb. 



Turnus sphenoideus (sp. nov.). Shell elongate-cuneate, inflated in front, 

 narrowed, and laterally flattened behind; beaks anterior, incurved, adjacent; 



