170 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



This species is not liable to be confounded with any other shell yet 

 discovered in any of the Upper Mo. rocks, and it seems to differ from all the 

 otherwise similar forms known from other localities, in having the small 

 tubercles in the depressions between the costse of uniform size, instead of 

 alternately larger and smaller. 



Locality and position. — Mouth of Judith River, in a sandstone of Creta- 

 ceous age, believed to hold a position at the horizon of the top of the Fox 

 Hills group. Numerous specimens of this species have also been found in 

 the highest beds of the Fox Hills group, by Dr. Hayden, on Cache La Poudre 

 River, Colorado. 



Cardium (!) Kansasense, Meek. 



Plate 2, figs. 14, o, 6, e, (I. 



Cardium Kansasense, Meek (1871), Hayden's Second Aim. Report Geo]. Survey of the Territories, 307. 



Shell rather small, oval-suborbicular, being generally slightly higher than 

 the antero-posterior diameter, and rather gibbous, with the greatest convexity 

 usually above the middle; pallial margin rounded, or subsemicircular in out- 

 line, being in most cases more prominent behind the middle ; anterior margin 

 more or less regularly rounded ; posterior outline rounded, or very faintly 

 subtruncated ; dorsal outline sloping abruptly from the beaks before and 

 behind; beaks elevated, gibbous, incurved, and subcentral, or a little in 

 advance of the middle, and but slightly oblique ; posterior dorsal slopes some- 

 what flattened ; surface marked by numerous regular, simple, radiating striae, 

 or small costae, that are sometimes interrupted by marks of growth. Hinge 

 strong, with cardinal and anterior lateral teeth stout; posterior lateral remote 

 and less prominent. Anterior muscular scar rather deep; posterior shallow. 

 Scar of pedal muscle (!) small, very deep, and situated on the inner anterior 

 side, and near the points of the beaks, almost opposite the cardinal teeth, as 

 shown at (p of fig. 14 d.) 



Length, <U)4 inch ; height, 1 inch ; convexity, about 0.63 inch. 



This and Protocardia Salinaensis an 1 the two most common shells found 

 at the locality where they were obtained, and being, like the other fossils 

 with which they are associated, found in the condition of casts, not always 

 showing even traces of the surface-markings, it is sometimes difficult to 

 distinguish them. Where any remains of the surface-markings can be seen, 

 however, they can lie at once distinguished by the concentric costse on the 



