21 

 CIOXODOE^, Cope. 



Bulletin of the United States Geological Survey of the Territories, 1874, p. 10.* 



Eemains of species of Dinosaiiria were obtained at two localities ia 

 Colorado not many miles apart, the greater number at one of them, from 

 which also all the crocodilian and turtle remains were derived. Those 

 from the other deposit consist of portions of limb-bones apparently of a 

 single individual of gigantic size. The more abundant fragments are 

 referable to three species. A fragment of a limb-bone is very similar to 

 portions from the other locality, and associated is a sacral vertebra of 

 appropriate size and characters. All of these were therefore referred 

 provisionally to a single species under the name of Agatliaumas milo^ 

 but are here described under Sadrosaurus occidentalis. The remaining 

 specimens fall into two series. In the one the bones are occupied by a 

 heavy mineral and the surfaces covered by a white layer which is marked 

 by irregular ridges, as though produced by deposit along the lines of 

 small adherent foreign bodies. In the other set the bones are lighter, 

 more spongy, and not covered with the white layer; some of them are 

 stained by the sesquioxide of iron. Both present vertebral and limb 

 bones, which are related appropriately as to size and structure ; that is, 

 the larger limb-bones have the same mineral character as the larger ver- 

 tebrae, and the smaller as the smaller. These limb-bones represent cor- 

 responding parts in the two, and diftering widely confirm, the belief in. 

 the existence of two species indicated by the different types of vertebrse. 

 In these fossils, then, I see evidence for the existence of two species of 

 two genera, which I name, the larger Polyonax mortuarlus, the smaller, 

 Cionodon arcfatus. Both genera present a solid cancellous filling of 

 femora, tibifc, and other long bones, and hence differ from such genera 

 as Uadrosaurus, Sypsibema^ Lcelaps, and others. Cionodon differs in 

 dentition from all Dinosauria where that part of the structure is known, 

 but it remains to compare Polyonax with Troodon and Palceoscincus of 

 Leidy, which are known from the teeth only, while no portions of denti- 

 tion are preserved with the specimens at my disposal. 



CJiar. genericus. Established primarily on a portion of the right max- 

 illary bone, with numerous teeth in place. The posterior portion exhibits 

 a suture, probably for union with the palatine bone, while the rest of the 

 interior margin is free. It is removed some distance from the tooth-line 

 in consequence of the horizontal expanse of the bone, while the outer 

 face is vertical. 



The teeth are rod-like, the upper portion sub-cylindric in section, with 

 the inner face fattened from apex to base, while the lower half is flattened 

 externally by an abrupt excavation to the middle, for the accommodation 

 of the crown of the successional tooth. The inner face of the tooth, from 

 apex to base, is shielded by a plate of enamel, which is somewhat ele- 

 vated at the margins, and supports a keel in the middle, thus giving rise 

 to two shallow longitudinal troughs. The remainder of the tooth is 

 covered with a layer of some dense substance, i^ossibly cementum, which 

 overlaps the vanishing margins of the enamel. The outer inferior exca- 

 vation of the shaft presents a median longitudinal groove, to accommo- 

 date the keel of the closely appressed crown of the successional tooth. 

 The apex of the tooth being obtusely wedge-shaped, the functional tooth 

 is pushed downward and transversely toward the inner side of the 

 jaw. The tooth shdes downward in a closely-fitting vertical groove of 

 the outer alveolar wall. The inner wall is oblique, its section forming, 

 with that of the outer, a V ; it is furrowed with grooves similar and op- 



* Where the proof-reader made it Cinodon. 



