GEOLOGICAL SURVEY OF THE TERRITORIES. 615 



size, while one behind the middle of the maxillary is larger than the rest. 

 The posterior teeth have short, very obtuse crowns, with elliptic fore and 

 aft outline. They resemble some forms seen in Pycnodout fishes, and 

 are closely striate to a line on the apex. The upper surface of the cra- 

 nium is pitted, the frontal aud parietal bones with large, deep, and 

 closely placed concavities. The former is perfectly plane, and the latter 

 is wide. The squamosal arch is also wide, and the crotophite foramina 

 are large and open. 



Tbe dermal scuta are very large for the size of the animal, and were 

 not united by suture. They are keelless and deeply pitted, with smooth 

 margins. » 



The vertebral centra found with other specimens are round. The 

 co-ossified neural arches indicate the adult age of the animal. 



Measurements. 



M. 



Height crown preniaxillary tooth 004 



Width crowu preuiaxilhiry at base 0035 



Long diameter crown of a maxillary 005 



Short dia'meter crown of a maxillary 0035 



Width parietal 009 



W^idth frontal, posterior 020 



W.idth frontal, interorbital 010 



W^idth malar below eye 008 



The variation in the form of the teeth is a slight exaggeration of that 

 seen in the dentition of various species of crocodilians. 



This species was about three feet in length, found by the writer in 

 one of the lowest beds of the Green Eiver Tertiary epoch, near Black 

 Buttes, Wyoming. 



The dermal scuta of this species are very abundant in some of the 

 beds of the Green Eiver epoch. Some of them exhibit a faint trace of 

 keel. Vertebrae associated with them have subround articular ex- 

 tremities. 



TE.STUDIKATA. 

 AXESTUS, Cope. 



Proceed. Amer. Philos. Society, 1872, p. 462. (Published July 29.) 



This is a genus of Triouychida^, which is represented by a species not 

 fully known. The type specimen is represented by bones of the limbs 

 and various vertebrae, with the postabdominal bone of the left side. 



The general characters are those of Trianyx. The scapula is elongate, 

 the procoracoid long and narrow, and the coracoid of medium width. 

 The humerus is sigmoid, with widely spreading bicipital ridges and flat- 

 tened extremity with marginal groove. The femur is also carved, but 

 less strongly than the humerus, and has a median anterior low angular 

 ridge. The claws are large, some curved and some entirely straight. 

 The cervical vertebrte are relatively large and elongate. The two sacrals 

 are free from' the carai)ace above, have broad articular surfaces for 

 diapophyses, and flattened centra. Tbe caudals are procoelian, and have 

 short diapophyses. The postabdominal bone has somewhat the form 

 seen in existing Trionyx. It presents two dentate processes forward 

 for the hyosterual, and two inward to its mate in front. It is pro- 

 longed backward and inward into a flat process. It is especially dis- 

 tinguished by its tenuity, and the entire absence of the superficial 

 sculpture of Trionyx. The usual dense layer is present, but is quite 



