96 Trans. Acad. Sci. of St. Louis. 



It is also closely allied to E. philipi Hall, also from the 

 Chemung. 



Edmondia jejunus (Win.). 



PI. IV. f. 5. 



Sanguinolites jejunus. Bull. U. S. G. S. No. 153: 538. 



" Shell of moderate size, equivalve, transverse; beaks small, 

 barely elevated above the hinge, slightly inflected, one-third 

 the shell-length from the anterior end; height fully half the 

 length; hinge-line extended; dorsal slope erect, marked by 

 an internal ridge; margin slightly inflected, if at all, though 

 some indication exists of a very narrow escutcheon ; anterior 

 lunette equally inconspicuous ; ventral margin symmetrically 

 arcuate between the extremities, with which it connects by 

 similar gradually increasing curvatures; posterior end truncate 

 for a short space near the termination of the hinge-line, with 

 which it forms an angle of about 130° ; anterior end semi- 

 elliptically rounded. Valves somewhat appressed; greatest 

 distension one-fourth the distance from the beak to the 

 center. Surface of cast marked by faint lines of growth. 

 Length 21 mm., height 12 mm." 



Remarks. This species was originally referred to the 

 genus Sanguinolites, but its characters, so far as they are 

 preserved, seem rather to ally it to the genus Edmondia. 

 It differs from most of the species of Edmondia, however, 

 in its greater proportional length. The specimen illustrated 

 is the best preserved one of the types of the species in the 

 University of Michigan collection, and as its dimensions cor- 

 respond with those given by Winchell, it is believed to be 

 the specimen from which he drew up his description. There 

 are two other specimens of the same species, both of which 

 are somewhat smaller than the one illustrated. 



Sphenotus rigidus (W. & W.). 



PL IV. f. 9. 



Shell elongate, subtriangular or elongate subpentagonal in 

 outline; length, 25 mm., breadth, 12 mm. Hinge-line straight 

 posteriorly, arcuate in front; anterior margin short, regularly 

 rounded, merging into the ventral margin below; ventral 

 margin straight, sometimes slightly emarginate a little in front 



