Loomis — Reptiles from the Titanothere Beds. 427 



Art. XLIII. — Two New River Reptiles from the Titanothere 

 Beds ; by F. B. Loomis. 



Although the Titanothere beds of the White River forma- 

 tion are usually regarded as of flood plain origin, the known 

 distinctively river animals are very few. Such forms as Elo- 

 therium and Csenopus lived along the river banks ; but of those 

 dwelling in the water itself, none has been described, although 

 occasionally a reference is made to fragments of Trionyx. The 

 Amherst College Expedition of 1903 found two well-preserved 

 river forms, which, together with a remarkable case of rede- 

 position of Cretaceous fossils in the White River beds, make 

 the basis of this paper. 



Several times in the Oligocene " Bad Lands " along the 

 Cheyenne River fragments of crocodilian dermal scutes were 

 found ; and, finally, in the Finney Breaks near Fulsom Post 

 Office, S. D., a specimen came to light, consisting of 10 verte- 

 brae, 25 dermal scutes, the femur, tibia, astragulus and a num- 

 ber of fragments. Then, in the museum of the South Dakota 

 School of Mines, Prof. O'Hara showed me a crocodilian snout, 

 found in the Titanothere beds in Indian Draw, distant some 

 six miles from the first specimen. This imperfect skull is used 

 as the type of the new species ; and the skeletal parts, inas- 

 much as they are of dimensions appropriate to the skull, are 

 referred to the same species, of which the following is the 

 description. 



Crocodilus prenasalis, nov. spec. Figs. 1-9; 1-6, Xi> ^ -9 > Xf 

 The front end of the cranium with nine tooth alveoli on 

 either side is preserved, together with the anterior part of the 

 lower jaw, still in position. The snout is broad and short, 

 indicating a wide head. The undivided nasal opening is very 

 far forward, and differs from that of other crocodiles in the 

 lack of a distinct anterior border," this portion of the nasal 

 cavity having a smooth, rimless boundary on the prsemaxilla. 

 The nostril opening would seem, therefore, to have been 

 directed to the front rather than upward on top of the snout. 

 (This lack of a rim gives the snout a distinctly mammalian 

 appearance.) The boundaries of the frontals are not distinct, 

 but if what appears to be the suture is correct, they are unusu- 

 ally wide. Their upper surface is covered with good-sized 

 pits. On the left side, just where the snout is broken off, is a 

 constriction on the maxilla to receive a tooth of the lower jaw. 

 This comes just behind the ninth superior tooth, but just 

 which tooth of the lower jaw would fit into it cannot be deter- 

 mined, as the two jaws are closely interlocked. The two 

 halves of the lower jaw are completely fused at the symphysis. 



