CRETACEOUS FOSSILS. 145 



Inoceramus erectus, Meek. 



Plate 13, figs. 1 and 1 a ; aiul pi. 1 1, fi-. :i. 



Compare Inocemmm Ellioltll, ihxhh (180S), PaUvont. ckf Califoruia, II, 103, pi. oi, 

 fig. 'JO. 



Shell attaining a uiediinu .size, vertieall}' ovatcs-obloiig, bein,!;;' higher 

 than wide, not oblique, very gibbous, and nearly or quite equivalve; hinge 

 shorter than the antero-posterior diameter of the valves, and ranging at right 

 angles to their longer (vertical) axes; basal margin regularly rounded; 

 anterior margin truncated nearly vertically from the front of the beaks more 

 than half-way down, but rounding into the base below, inflected in both 

 valves along the rather gibbous anterior umbonal slopes, so as to form a long, 

 undefined, lunule-like excavation, that extends more than half-way down from 

 the beaks; beaks not very prominent, abruptly pointed, very nearly equal, 

 incurved with rather slight obliquity, and placed nearly directly over the 

 vertical anterior margin. Surface of both valves ornamented by regular, 

 medium-sized, concentric undulations, which are usually obsolete on the 

 posterior dorsal region and the inflected anterior margins. 



Height, about 2.50 inches; length, 2 inches; convexity, 2.30 inches. 



As I have only seen imperfect specimens (mainly casts in sandstone) 

 of this shell, and Mr. Gabb merely gives a single side-view of one speci- 

 men of the California species I. EUiottii, without measurements, I have 

 doubts in regard to the relations of these shells. In outline, as seen in a 

 side-view, it agrees well Avith Mr. Gabb's figure cited above, excepting that 

 it appears to be more convex than his shading would indicate, and has 

 more obtuse undulations. 



[Since writing the above, I have, through the politeness of Mr. Gabl), 

 had an opportunity to compare our shell with the type of his I. Elliottu, and 

 I am led to regard the two as belonging to distinct species. The California 

 form is, as 1 had inferred from Mr. Gabb's figures, much more compressed; 

 while its surface undulations differ decidedly in being very acutely angular. 

 As I have not been able to identify our shell with any other described 

 species, I add the name I. erectus for it here as this report is passing through 

 the press.] 



Localitjj and imitlon. — Chalk Creek, near Uptuwii, Utah; Cretaceous. 



10 1' R 



