NODOSAURID.R 225 



PAL^OSCIJJCUE. 



A new reptilian genus and species, Palceoscincus co&tatus, was pro- 

 posed by Dr. Leidy, in 1S56, for a single tooth found by Dr. Hayden in 

 the Judith Basin. This tooth was more fully described and figured by 

 Leidy in 1S59. The specimen showed well-marked characters, and 

 many similar teeth have since been found, both in the Judith Basin 

 and in various other localities of the same horizon. 



A smaller species, apparently of the same genus, is not uncommon 

 in the Ceratops beds of Wyoming, and a characteristic tooth is shown 

 on PL LXXY, fig. 3. This is the type specimen of the species Palceo- 

 scincus latus. The crown of the tooth in this species is broader and 

 the apex more pointed than in the first species described, and this is 

 clearly shown in comparing the present figures on PI. LXXY with those 

 given by Leidy. 



NODOSA VRIDJE. 



NODOSATTRTJS. 



Another genus of Stegosauria, from a lower horizon in the Creta- 

 ceous, was discovered several years since, in Wyoming, and the type 

 specimen is now in the Yale museum. This geuus, Xodosaurus, was 

 described by the writer in 1889. The skull is not kuown, but various 

 portions of the skeleton were secured. One characteristic feature in 

 this genus is the dermal armor, which appears to have been more com- 

 plete than in auy of the American forms hitherto found. This armor 

 covered the sides closely, and was supported by the ribs, which were 

 especially strengthened to maintain it. In the present specimen por- 

 tions of it were found in position. It was regularly arranged in a series 

 of rounded knobs in rows, and these protuberances have suggested the 

 generic name. 



Xear the head the dermal ossifications were quite small, and those 

 preserved are quadrangular in form, and arranged in rows. The 

 external surface is peculiarly marked by a texture that appears inter- 

 woven, like a coarse cloth. This has suggested the specific name, and 

 is well shown in PI. LXXY, fig. 5. 



The fore Hmbs are especially massive and powerful, and are much 

 like those of the Jurassic Stegosaurus. There were five well-developed 

 digits iu the manus. and their terminal phalanges are more narrow 

 than usual in this group. The ribs are T-shaped in transverse section, 

 and thus especially adapted to support the armor over them. The 

 caudal vertebrae are more elongate than those of Stegosaurus, and the 

 middle caudals have a median groove on the lower surface of the 

 centrum. * 



The animal when alive was about 30 feet in length. The known 

 remains are from the middle Cretaceous of Wyoming. 

 16 geol, pt 1 15 



