CRETACEOUS FOSSILS. 303 



mocERAarus subl^vis. 



Plate 10, figs. l-:i. 



Inoceramtiss sublcrvls U. & M., Mem. Am. Acad. Arts iuid Sci., now sor., vol. v., i). .380, 



PI. 2, fig. 1. 

 Inoceramus snblcevis (H. & M.) Meek, Pal. U. S. Geol. Surv. Terr., p. 58, PI. 12, fig. 1. 



Shell below medium size, suboval in outline, moderately gibbous, with 

 almost evenly convex valves, which are slightly more ventricose on the 

 umbones; beaks small, inconspicuous, incurved, and situated near the ante- 

 rior end; hinge line straight, two-thirds as long as the whole length of the 

 shell; anterior end rounded, projecting but little beyond the line of the 

 beaks, the greatest projection at about one-third the height of the valve, 

 below which the border, including the base and posterior end, forms a nearly 

 regular section of an oval curve. 



Surface of the specimens, where a portion of the nacreous layers are 

 presei'ved, presenting distinct, somewhat interrupted radiating lines, or lines 

 of pustules, with a few very faint indications of concentric undulations. 



A number of individuals among the collection, presenting similar feat- 

 ures, we have referred to this species. Their regularly symmetrical form 

 and smooth surfaces, marked by faint to distinct radiating lines, are features 

 that at once attract attention and render them easily distinguishable among 

 the other species of the genus. The radiating lines, as indicated on the 

 exfoliated shells, are still more conspicuous on the complete casts of the 

 interior, one of which is figured on the plate, and presents lines of elon- 

 gated pustules, making a conspicuous feature. 



Formation and locality. — In Cretaceous, No. 4, at the Forks of the 



Cheyenne ; and about three miles east of Camp Jenney, Red- Water Valley, 



Black Hills. 



INOCERAMUS SAGENSIS. 



Plate 7, fig. 12; PI. 8, fig. 2. 



Inoceramus sagensis Owen, Geol. Rept. Wis., Iowa, and Minn., p. 582, PI. vii, fig. 3, 1852. 



f Inoceramus nebracensis Owen, ib., p. 582, PI. viii, fig 1. 



Inoceramus sagensis var. Nebracensis (Owen) Meek, Pal. U. S. Geol. Surv. Terr., p. 52, 



PI. 13, fig. 2. 

 Compare Inoceramus convexus H. & M,, Mem. Am. Acad. Arts and Sci., new ser., vol. v, 



p. 386, PI. 2; Pal. U. S. Geol. Surv. Terr., PI. 12, fig. 5. 

 Compare Inoceramus balchiiM. & H., Proc. Acad. Nat. Sci. Phil., vol. xii, p. 180; Pal. U. 



S. Geol. Surv. Terr., 50, PI. 15, fig. 1. 



