STANTON.] AVICULIDvE. 77 



group. It has also been found at about the same horizon near Fort Ben 

 ton, Montana, in the Black hills of Dakota, and at the Vado del Charaa, 

 New Mexico. It occurs about 350 feet above the base of the Cretaceous 

 section in the Upper Kanab valley, southern Utah ; also in Lower Potato 

 valley and on Ashley's fork, Utah; at the latter place in strata that 

 were probably erroneously referred to the Fox Hills. It is abundant in 

 the Pugnellus sandstone which caps the Benton shales in Huerfano 

 park, Colorado. 



Inoceramus labiatus Schlotheim. 



PL x, Fig. 4; PL xiv, Fig. 2. 



08tracAte8 labiatus Schloth., 1813, Broim's Jahrb., vol. vn, p. 93. 



Mytulites problematicus Schloth., 1820. Petrefactenk. I, p. 302. 



Inoceramus mytiloides Mantel], 1822, Geol. of Sussex, p. 215, PL 28, Fig. 2. 



"(Inoceramus confertim-annulatus Scbiel, 1855, Pacific R. R. Reports, vol. II, Pt. 2, p. 108, 



PI. 2, Fig. 7. 

 1 1noceramus pseudo-mytiloides Schiel, 1855, Ibid., PL 3, Fig. 8. 



Inoceramus mytiloides (Mantell) Roem., 1852, Kreide. von Texas, p. 60, PL 7, Fig. 5. 

 Inoceramus mytilopsis Conrad, 1857, U. S. Mexican Boundary Sur., vol. I, Pt. 2, p. 152, 



PL 5, Figs. 6a and 6b. 

 Inoceramus problematicus (Schloth.) Meek, 1876, U. S. Geol. Sur. Terr., vol. ix, p. 62, PL 



9, Figs. 3 a and b. 

 Inoceramus aviculoides M. and H., 1860, Proc. Acad. Nat. Sci., Phila., p. 181. 

 Inoceramus problematicus var. aviculoides Meek, 1876, U. S. Geol. Sur. Terr., vol. ix, p. 



63, PL 9, Fig. 4. 

 Inoceramus problematicus, mytiloides or labiatus of many authors. 



The following is Meek's description of the species : 



u Shell obliquely elongate-oval, subelliptical or ovate, nearly or quite 

 equi valve, rather compressed, thin and fragile; anterior side forming a 

 slightly convex curve from the beaks obliquely downward and back- 

 ward; posterobasal extremity rather narrowly rounded; postero-dorsal 

 margin very oblique, compressed, nearly straight, or sometimes a little 

 convex in outline below the middle, aiid slightly concave above ; cardi- 

 nal border short, straight, compressed, and forming an angle of about 

 45 degrees with the longest diameter of the shell ; beaks terminal, 

 rather small, nearly equal, obtusely-pointed, rising little above the 

 hinge, and not much incurved. Surface ornamented by more or less 

 regular, concentric undulations, and smaller marks of growth. 



"Greatest length, 4 inches; breadth, at fight angles to the longest 

 diameter, about 2 inches; convexity of the two valves, about 0.80 inch." 



The name Inoceramus aviculoides was applied by Meek and Hayden 

 to a variety with a longer hinge line, greater convexity and more prom- 

 inent beak of the left valve, and with the dorsal region more alate than 

 is usual in the species. After studying larger collections Prof. Meek 

 found that there were many graduations between this and the typical 

 form, and he therefore treated it as only a variety. Like all species of 

 the genus, it is subject to considerable variation in form, yet it is 



