lo 5. W. WILLISTON 



stomous form. They were collected during the past season by Mr. 

 Reed in the vicinity of Wilcox, Wyo., in a dark shale of the Graneros 

 division of the Benton, and below the heavily laminated shales which 

 must be ascribed to the Mowrie beds of Darton. I have recognized 

 what I beheve to be the same horizon, also fossiliferous, two hundred 

 miles or more to the northwest in Wyoming, lying below the lami- 

 nated shales yielding numerous fish scales and fish bones. The 

 Hailey shales lie some four hundred feet higher than this horizon, 

 above the Mowrie shales, and above thin layers of limestone which 

 may represent the Greenhorn limestones of Darton. Mr. Reed has 

 traced the Wilcox fossiliferous horizon for about thirty miles into 

 Carbon County on Troublesome Creek, where it also yields verte- 

 brate fossils. 



The fossils sent me are for the most part more or less fragmentary 

 and water-worn. They include two or three species of plesiosaurs, 

 one of which seems closely allied to Trinacromerum anonymum Wil- 

 liston, from the Benton of Kansas ; various fragments of the carapace 

 and plastron of a large, thick-shelled turtle; the spine of a shark, not 

 unlike those of Com.T from the Cretaceous of Kansas; small shark 

 teeth; and a large premaxillary bone with a single long tooth, whose 

 systematic position I have not yet determined. 



I can distinguish but a single species, among the crocodilian 

 remains preserved, though they differ greatly in size and may in 

 reality be of different forms. Of course, none of the bones can be 

 associated together as of one individual. 



The ilium (Fig. i) differs from that of a modern crocodile in the 

 greater elongation of the posterior process, and in the relatively less 

 width of the bone. An ischium (Fig. 5) of a smaller individual dif- 

 fers in the less expansion of the distal end, its more rounded posterior 

 angle, and the greater obliquity of the shaft of the bone. The pubes 

 of several individuals are represented by more or less fragmentary 

 parts, all of about one size. One nearly complete specimen is shown 

 in Fig. 2. It is also noticeable for the slenderness of the shaft, and 

 the moderate dilatation of the distal extremity, differing markedly in 

 this respect from the known forms of Gbniopholis and Bernissartia. 

 The upper extremity of a humerus of a large individual is shown in 

 Fig. 3. Its curvature is slight, much less than of a humerus of nearly 



