294 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



" Shell elongate-subelliptic in outline, much compressed ; extremities 

 nearly equally rounded ; pallial margin straight and nearly parallel to 

 the dorsal, but rounding up regularly at both ends; dorsal side straight 

 or very slightly convex in outline ; beaks depressed nearly or quite to 

 the dorsal margin and placed about one-fourth the length of the valves 

 from the anterior end ; anterior muscular impression ovate, rather well 

 defined, and with its longer diameter ranging vertically ; pedal scar dis- 

 tinct, near the upper end of that of the anterior adductor ; posterior mus- 

 cular impression very shallow ; pallial line with its sinus rather deep, 

 horizontal, and obtuse at the end. Surface with lines and some small 

 ridges of growth. 



" Length, 1.70 inches; height, 0.82 inch; convexity, about 0.28 inch." 



Mr. Meek also makes the following remarks concerning the relations 

 of this shell : . 



" The only specimens of this species yet obtained are mainly casts retain- 

 ing some portions of the shell. They give very little idea of the nature of 

 the hinge beyond the fact that it seems to have three diverging cardinal 

 teeth, the exact form and arrangement of which cannot be made out. 

 The general expression of the shell, however, is very nearly that of some 

 European Cretaceous forms that seem to have essentially the hinge char- 

 acters of Tapes, though they may not be exactly congeneric with the re- 

 cent species of that genus. Among the foreign species our shell seems 

 to be most nearly represented by Venus fragilis d'Qrbigny (from the Cre- 

 taceous of France), which is not a trneVemiSj but has been referred by 

 Mr. Zittel to the genus Tapes. (See Bivalvender Gossaug. NordAlpen. 

 Compared with d'Qrbigny's figure and description of his V. fragilis, 

 given in the Paleont. Francaise, our shell differs in being regularly 

 rounded instead of truncated posteriorly. It is also straighter on the 

 basal margin and more broadly rounded in front. In some of these 

 characters it agrees more nearly with Professor Zittel's figures, which I 

 suspect may represent a distinct species from that figured by d'Orbigny. 

 Still it differs from Professor Zittel's figures in having its anterior margin 

 more broadly rounded and its pallial margin straighter in outline. 



" Locality and position. — Mouth of Deer Creek, on North Platte, in 

 Wyoming Territory; Fox Hills Group of the Upper Missouri Cretaceous 

 series." 



Two years after this description was written, Mr. Meek referred this 

 species to the genus Baroda Stoliczska (loc. cit.) in which he was proba- 

 bly right, although nothing further is known concerning the hinge of 

 the species. It is evidently congeneric with the following species, which 

 I also refer to Baroda. 



Baeoda subelliptica (sp. nov.)^ 



Plate x, figs. 4 a, 1), c, and. d. 



Shell subelliptical in marginal outline, moderately compressed, that is, 

 the valves have comparatively slight convexity ; anterior and posterior 

 extremities both somewhat regularly, nearly equally, rounded, the poste- 

 rior being a little narrower than the front ; basal margin broadly convex 

 and regularly rounded upward, both anteriorly and posteriorly ; dorsal 

 border broadly convex and regularly rounded downward, both anteriorly 

 and posteriorly; beak small, moderately prominent, and placed nearly 

 midlength of the shell. The hinge is not fully known, but as that of the 

 left valve is partially shown by the larger of the two examples figured 

 on plate x, it appears to be furnished with three teeth. Two of them are 



