Weller — Kinderhook Faunal Studies. 171 



curved, furnished with a pair of rather thick lateral teeth ; 

 cardinal teeth apparently none. Surface marked, toward the 

 margin, by a few irregular concentric wrinkles." 



Length 20 mm., height 15| mm., convexity of a single 

 valve 5 mm. 



Remarks. In the original description this species is said to 

 be marked by " fine radiating lines," but this statement is 

 omitted from the above quotation. The types of the species 

 are three in number, but one of these, the one showing the 

 radiating lines, is not even cogeneric with the others. The 

 dissimilarity between this specimen and the other two was 

 probably recognized by Winchell subsequent to the prepara- 

 tion of the description of the species, for this specimen is 

 indicated on the card to which all three are attached, " Dexi- 

 obia whitei " and the specimen may be a left valve of this 

 species. Of the two remaining specimens, a drawing has 

 been made of the best preserved one, and is here published. 

 It is very similar to E. nuptialis, and in all probability E. 

 strigillata should be considered only as a synonym of that 

 species. 



Sphenotus cylindricus (Win.). 

 pi. xv. f. 11. 



Sanguinolites cylindricus, Bull. U. S. G. S. 153: 538. 



Original description. "Shell small, equivalve; length 

 equal to two and a half times its height ; beak about one- 

 seventh the length from the anterior end, elevated above the 

 hinge-line, flattened and enrolled; greatest height along the 

 perpendicular from beak to base; dorsal margin extended, 

 slightly concave upwards and inwards, sharply inflected in- 

 wards, forming a long, deep posterior escutcheon or cartilage 

 base ; ventral margin nearly straight, curving rapidly from a 

 point opposite the beaks to the anterior extermity, which is 

 abruptly rounded into the deep heart-shaped lunette ; posterior 

 extremity truncated by a line extending from the basal to the 

 dorsal margin, and making with the latter an angle of 120°. 

 Valves very ventricose, the greatest thickness being behind 

 the central point on the sharp, prominent umbonal plication, 

 which extends from the beak to the postero-basal angle — the 

 area between this plication and the anterior region being 



