COPE.] PALEONTOLOGY CRETACEOUS PERIOD VERTEBRATA. 447 



Eeferred, by Professor Leidy, to a distinct geuus under the name of 

 Thespesius, on account of the slightly opisthocoeliau character of the 

 large caudal vertebra. Teeth unknown. 



Fragments of a large dinosaur from Colorado were found associated 

 with species of tortoises identical with those found in Dakota in the 

 horizon which contains the S. occidentalism (see under head of Cionodon 

 arctatus,) and may possibly belong to it. I have no identical parts in 

 the two for comparison. 



Char, specif. — The largest fragment of a long bone is probably from 

 the i)roxiu)ai. end of the tibia ; it includes the curved inner border of 

 the side, and the inner posterior tuberosity, with five inches of the inner 

 head side of the shaft. The superficial layer is marked with numerous 

 closely-placed longitudinal grooves, which are replaced by a few coarser 

 and deeper ones, which interrupt the angle with the articular surface, 

 giving it a lobate margin. There was probably a prominent cnemial 

 crest. Another fragment exhibits one flat plane and a concave posterior 

 face. It comes from near the extremity of the humerus or the femur; 

 it was found near the fragment of the tibia. The sacral vertebra is proba- 

 bly that of an animal not fully grown, as it v^as not co-ossified with 

 those adjacent. The articular extremities are expanded, and present 

 distinct faces for articulation for the large diapophyses. The one ex- 

 tremity is more expanded and less thickened; the other more thickened 

 and less dilated; on this rests the greater part of the base of the neural 

 arch. Just at the extremity of this base, the large sacral nervous for- 

 amen issues, which is continued in a wide groove downward between the 

 transverse expansions. Inferior surface convex. As compared with 

 the fourth sacral vertebra of Agathaumas sylvestris, Cope, which it nearly 

 resembles in size, it is to be observed that the anterior extremity is less 

 expanded transversely as compared with the posterior ; that the 

 bases of support for the anterior diapophyses are not i^roduced down- 

 ward so far; that the sides of the centrum are nearly vertical and not 

 sloping obliquely toward the middle line; and that there is no inferior 

 plane separated from the lateral by a longitudinal angle as in A. sylvestris. 

 It differs in like manner from the third and second sacral vertebrae, and 

 still more from the first of the latter saurian. 



Measurements. 



M. 



Length of centrum of fourth sacral vertebra 002 



f in front \ 103 



Transverse diameter-? at middle 072 



( j)Osteriorly 121 



Vertical diameter posteriorly 092 



Diameter of head of tibia autero-posteriorly 250 



CIONODON, Cope. 



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



Eemains of species of Dinosauria were obtained at two localities in 

 Colorado not many miles ai)art — 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 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 



* Where the proof-reader made it Cinodon. 



