INVERTEBRATE PALEONTOLOGY. 121 



below; dorsal outline sloping rather abruptly in front of the beaks, and less 

 distinctly so behind; beaks moderately prominent, and placed a little in 

 advance of the middle; posterior umbonal slopes prominently rounded from 

 the beaks to posterior basal extremity; posterior dorsal region above the 

 umbonal prominences flattened; flanks sometimes a little concave toward the 

 pallial margin. Surface with rather distinct lines of growth. 



Length, 0.73 inch; height, 0.32 inch; convexity, 0.30 inch. 



Specifically, this shell is more nearly like a species I have described from 

 the Cretaceous near Canon City under the name of Mactra? Canonensis than 

 it is like any other form with which I am acquainted; though it differs too 

 widely to be confounded with that shell, even where the hinge could not be 

 seen. They both have so much the appearance of the genus Orassatella 

 externally, that few would hesitate to refer them to that genus, where their 

 external characters only could be examined. 



Locality and position. — Twelve miles southwest of Salina, Saline County, 

 Kansas; Dakota Group of the Upper Missouri Cretaceous series. Collected 

 by Professor B. F. Mudge. 



Genus ERIPHYLA, Gabb. 



Synon.—Eriphyla, Gabb (1864), Pabeont. California, I, 180.— Stoliczka (1871), Patoont. lud. Ill, 156 (but 

 not ib., 181 and 182, pi. vi,= Dozia, Bosquet, 1868). 



Etym. — ipupi'lri (Eriphyla), tbe wife of Amphiarius. 

 Type. — E. umbonata, Gabb. 



Shell subtrigonal, nearly ecpiilateral ; surface concentrically costate and 

 sulcate, or striated : ligament external ; lunuledeep; hinge with two cardinal 

 teeth in the right valve, and one in the left, and an elongated anterior and 

 posterior lateral tooth in each valve; pallial line unknown. 



Mr. Gabb remarks that the type of this genus is related to Astarte and 

 Gouldia, more particularly to the latter; but that it may be readily distin- 

 guished from the former by its well-developed lateral teeth ; and from the 

 latter, by having posterior as well as anterior lateral teeth. Mr. Gabb also 

 remarks that the left valve sometimes shows traces of a posterior rudimentary 

 second cardinal tooth, that is received into a corresponding small pit just 

 behind the larger posterior cardinal tooth of the other valve; and that other 

 species may possess two well-developed cardinal teeth in each valve, in 

 consequence of the greater size of this rudimentary cardinal of the left 



valve. 



1G n 



