124 PROCEEDINGS OF THE ACADEMY OF 



notched much in the same manner as in the Snapper. The intermediate ver- 

 tebral scute impressions have nearly the form and proportions as in the latter, 

 but are not carinated in the median line, and the posterior line of the fourth 

 vertebral scute impression is deeply and widely notched forward. 



The sternum is very unlike that of the Snapper, and rather approaches that 

 of the emydes in its form and proportions. The interspaces of the carapace 

 and sternum are, however, intermediate in capacity to those in the former 

 and latter. The sternal pedicels are deep and wide, and are impressed by a 

 pair of large scutes, separating the large axillary and inguinal scute, as in the 

 existing Dermatemys. The posterior extremity of the sternum in outline is 

 half oval and feebly notched. 



When complete the shell has measured between a foot and fourteen inches 

 in length and about ten inches in breadth. The sternum has been about ten 

 and a half inches long; its pedicels are f>\ inches deep; and its posterior ex- 

 tremity is 3 inches long by 4^ inches wide at base. 



For the genus I have adopted a name which, according to Prof. Hayden, is 

 used by one of the Indian tribes of the Upper Missouri as that of a turtle. 

 The species I propose to name Baena arenosa. 



Saniwa ensidexs. Among the fossils obtained in Prof. Haydeu's expedi- 

 tion are the remains of a lacertian, labeled as having been discovered near 

 " Granger." The bones consist of those of most parts of the skeleton, but are 

 all in a fragmentary condition, and are imbedded in freshly broken pieces of 

 an ash- colored rack. Before disturbance they appear to have been mostly 

 entire and preserved nearly in conjunction. They are black, and their inte- 

 rior is occupied with crystalline calcite. 



Fragments of bones exhibit well developed limbs, with long toes, strong 

 ribs, and a long tail, altogether indicating a form like that of ordinary living 

 lacertians. The long bones, even to those of the toes, are hollow. The ver- 

 tebrae exhibit the ball and socket articulation of their bodies, but only a sin- 

 gle pair of zygapophyses iu front and behind. No zygantral and zygosphenal 

 articulation appears to have existed. 



The articular ball of the vertebral body is much wider than high, and is 

 directed upward, with an inclination backward. 



The body of several dorsals is quite straight inferiorly. fore and aft, and 

 measures half an inch in length. The ball is four lines wide, and about half 

 as thick. The breadth at the anterior zygapophyses is eight lines, and at the 

 articulations for the ribs, just exterior to the latter, three-fourths of an 

 inch. 



An anterior caudal has its body the same length as in the preceding. Its 

 ball is 3i lines by 2\ thick. The width at the anterior zygapophyses is half 

 an inch. 



Hypapophyses for the articulation of chevrons are situated one-fourth the 

 length of the body from the posterior extremity. 



A tooth was found, after careful search, in proximity to what appear to be 

 traces of the skull. It consisted of the crown, broken from its connection, 

 the character of which therefore cannot be ascertained. 



The crown of the tooth is compressed conical, slightly curved inwardly and 

 backward, sharp-pointed, with abruptly impressed trenchant borders ; is 

 smooth and shining. It is hollow and has thick walls. The transverse sec- 

 tion is rhomboidally oval, with acute poles. The length is about \\ lines; the 

 breadth f of a line ; the thickness \ a line. 



The remains would indicate an animal as large as the largest of our living 

 iguanians. 



For the generic name of the animal I would propose to use the euphonious 

 one of Saniwa, which, according to Prof. Hayden, is that used by one of the 

 Indian tribes of the Upper Missouri for a rock lizard. The species may be 

 named Saniwa ensidens. 



[Nov. 



Issued November 29th, 1870. 



