no 



In the comparative length of its hinge line, this Inoceramus somewhat 

 resembles the Nebraska variety of I. problematic us de.-^cribed and tigui'ed 

 by Meek as /. jjroblematicus, var. aviculoides.''' 



Inoceramus Vancouv^erensis, Shumard. 

 Plate 20, figures 4, 4ff and 4^. 



Inoceramus Vancouvei-ensis, Shumard. — Trans. Ac. Sc. St. Louis, Vol. I., (1858) p. 



123. 

 ?= Inoceramus Mliotii, Gahh. —Pal. Cal. Vol. II., (1869) p. 193, pi. 31, 



fig. 90«. 

 ?= Inoceramus alius, Mctik. — Hayden's Rep. G-eol. Surv. Terr., 1871, p. 



302. 

 «« " " " — Rep. Inv. Cret. and Tert. Foss. U. Miss, Co.> 



p. 43, pi. 14, figs, la, b. 

 Compare Inoceramus' propuiquus, Munster. — Goldfuss. Petr. Germ. Vol. II , (1840) p. 



112, pi. 109, figs. 9a, h. 



"Shell large, ovate subquadrate, not very oblique, gibbous and sloping 

 gradually* but somewhat irregularly to the basal margin, height equal to 

 or greater than the length; cardinal margin straight or very -slightly 

 arched ; buccal and basal margins regulai-ly rounded, and forming 

 together nearlj^ a semicircle; anal side lengthened, its margin gently 

 arched, and forming, with the cardinal margin, rather more than a right 

 angle; umbo verj" ventricose above; beaks directed obliquely forward, 

 incurved, very elevated, obtusely jjointed, situated neai'est the buccal 

 margin; surface marked with broad, rounded, unequal concentric folds, 

 and fine, nearly equidistant, slightl}^ prominent concentric lines. In 

 very young specimens a few longitudinal stria^ are to be seen passing 

 over the umbo, which, in most specimens in the collection, becomes 

 suddenly very ventricose, and forms a circumscribed, ovate tumor. 

 In other specimens, however, although there is a swelling of this part of 

 the shell, it does not rise so abruptly from the general surfiice. This 

 latter variet}^ of our shell resembles somewhat Inoceramus convexus 

 (Hall & Meek), from which it is easily distinguished by the concentric 

 lines of the surtace, which are much wuler apart. The I. Vancouver ensis 

 is also much less oblique, and this character also separates it from 

 I. Sat/ensis (Owen), to which it bears some resemblance." 



" Dimensions. — The measurements of the best specimen in the collec- 

 tion are — length, four inches ; height, four inches ; thickness of left valve, 



• Report on the Uivertebrate Cretaceous and Tertiary Fossils of the Upper Missouri Country, 

 p. 63, pi. 9, flg. 4. 



