176 PROCEEDINGS OF THE ACADEMY OP 



by fine irregular, obscure, concentric striae. Length, 0-38 inch ; height, 0-32 

 inch ; convexity 0.08 inch. 

 Locality and position. Near the mouth of Grand River on the Upper Missouri. 



Sph^rium recticardinale, M. & H. Shell of medium size, transversely 

 subelliptical, rather compressed, very thin; anterior side rounded ; base form- 

 ing a regular seraielliptic curve; posterior extremity obliquely subtruncate above, 

 and rather narrowly rounded below ; cardinal margin long and straight ; beaks 

 very small, compressed, and projecting but slightly above the hinge, located 

 nearly half way between the middle and the anterior end ; surface marked by 

 moderately distinct, irregular lines of growth. Length, 0-55 inch ; height, 0*36 

 inch ; breadth, 0-24 inch. 



Locality andposition, same as last. 



Cyrena (Corbicdla?) cytheriformis, M. & H. -Shell broad trigonal ovate, vary- 

 ing to subcircular, ratner thick and strong; extremities more or less rounded; 

 base semiovate, usually more prominent before than behind the middle ; dorsal 

 outline sloping from the beaks, the anterior slope being more abrupt than the 

 other, and slightly concave, while the posterior is convex ; beaks rather ele- 

 vated, moderately gibbous, located in advance of the middle ; surface marked 

 by fine lines of growth, which sometimes show a very slight tendency to gather 

 into small irregular concentric wrinkles. Length, inches ; height, inch ; 

 thickness, inch. 



Locality and positio?i. Estuary beds, near mouth of Judith River. 



CRETACEOUS SPECIES. 



CEPHALOPODA. 



Genus Phylloteuthis, M. & H. 



Phylloteuthis subovatds, M. &. H. The specimens on which we propose to 

 found this genus and species consist of the expanded portion of the pen or 

 gladius. This organ seems to have been corneous, and is thin, very wide or 

 subovate in form, a little concave on the under side, and convex above. From 

 behind the middle it narrows towards the front, the outline of the lateral mar- 

 gins being convex, while the posterior end is more or less obtusely angular. 

 The shaft is broken away in our specimens, but that portion of it extending 

 backward and forming the midrib of the expanded part, is narrow, prominent, 

 and rather sharply carinate above, while on the under side it is merely repre- 

 sented by a narrow groove. The lateral expansions are crossed a little ob- 

 liquely backward and outward, at an angle of about 65 from the midrib, by 

 numerous slender, ridged parallel striae, which are very nearly straight, or very 

 slightly curved backward near the outer margins. Length of expanded part, 

 exclusive of the shaft, 1-55 inch; breadth of do., 0-82 inch. 



Apparently near the Liassic genera Beloteuthis and Teudopsis, or at any rate 

 to species that have been, with doubtful propriety, ranged in these groups. 



Locality and position. Moreau River, in formation No. 5. 



Helicoceras angulatum Of this shell we have seen but a single nonseptate 

 fragment, 2-78 inches in length, with a diameter of 1-50 inches at the larger end, 

 and 1-37 inches at the smaller. It is rounded, or subcylindrical, and makes a 

 broad (sinistral?) spiral curve, in such a manner that if continued around, the 

 volutions would be disconnested, and encircle an umbilical cavity apparently 

 more than three times their own breadth. The surface is ornamented by dis- 

 tinct angular costae, which pass around the whorls obliquely and support two 

 rows of nodes on the lower outer side, where they sometimes bifurcate. Septa 

 unknown. 



Locality and position. Head of south branch of Shyenne River, in the upper 

 part of formation No. 4, of the Nebraska series. 



[May, 



