1 882.] The Reptiles of the 



Lacertilia. 



Of lizards I have obtained the remains of a half dozen 

 of species, but none of them in a complete state of preser- 

 vation. Professor Marsh has been more fortunate, as he de- 

 scribed from his material from the Bridger beds, twenty-one spe- 

 cies. 1 He arranges these under five generic heads, as follows : 

 Thinosaurus Marsh, five species ; Glyptosauras Marsh, eight spe- 

 cies; Xestops Cope (1873, Oreosaurus Marsh, not Peters), five 

 species ; Tinosaurus Marsh, two species ; and Iguanavus Marsh, 

 one species. As Professor Marsh does not give us any clue to 

 the affinities of these forms, they cannot be further considered 

 here. In Lieutenant Wheeler's Survey Report 2 I have pointed 

 out that the dermal scuta and a few other fragments which I ob- 

 tained in the Wasatch beds of New Mexico, were probably refer- 

 able to the Placosaurida, a family created by Gervais to receive 

 certain Lacertilia of the Eocene of France. To this family no 

 doubt some of the species described by Marsh from the" Bridger 

 horizon are to be referred. 



The Puerco epoch is characterized by the presence of the sub- 

 order Choristodera, of which one genus, Champsos aunts Cope, 

 holds over from the Laramie Cretaceous. These were large and 

 medium sized animals, somewhat resembling Crocodiles. They 

 have, according to Lemoine, who has discovered them in France, 

 ambulatory limbs, adapted for swimming. 

 Ophidia. 



The snakes of the Eocene are not very numerous as to species. 





FlG. i.—Palceophis littoralis Cope, from New Jersey. (Original.) 

 Palceophh halidanus Cope, from New Jersey. (Original.) 



'American Journal of Science and Arts, 1S71. June, :m<\ October, 1872. 

 'Vol. iv, pt. ii r p. 42, pi. xxxil, fig. 26-36. 



