PREPARATION AND RESEARCH IN AMERICAN MUSEUM 385 



of the material. The pairing of the girdle and limb bones was similarly 

 undertaken, though no attempt was made to pair the ribs. In a few cases 

 it has been possible to determine the relation of some of the girdle and 

 limb bones with the vertebrae, but in most cases the original association 

 is still unknown, though their possible association is very evident. 



CARXIVOROUS DIXOSAUR MATERIAL AXD TYPES 



Associated with typical theropod remains in the type of Epanterias 

 amplexus are some bones of a large opisthocoelian. It is possible, if not 

 probable, that the t3"pes of Tichosteus lucasanus and T. cequifacies, also 

 of SympTiyroylius musculosus, may be referable to the Theropoda. There 

 are some ribs among these which certainly do not agree in characters with 

 the majority of camarasaur ribs and do resemble those of the Theropoda. 

 They may be provisionally referred to a large member of the Theropoda. 

 Cope's type of Lcelaps trihedrodon and of Hypsiroplius discurus were also 

 collected at this locality. The former of these is certainly a therapod; 

 the position of the latter is uncertain. 



CHARACTERS OF THE GENUS CAMARASAURUS 



The results of the investigations described above include determina- 

 tions of the generic characters of Camarasaurus and Ampliicoelias, so far 

 as these characters are determinable from the material in the collec- 

 tion. The genus Camarasaurus is characterized by massive proportions. 

 Throughout the skeleton, with the single exception of the ischium, the 

 bones are stoutly constructed. 



The cervical vertebrae have divided spines ; otherwise they are not char- 

 acteristic. They resemble very closely the cervicals of Apatosaurus (syn. 

 Brontosaurus) . 



The dorsal vertebrae are characteristic. In addition to their general 

 stoutness, the dorsals possess a number of diagnostic characters. The 

 spines are low and broad. They possess a distinct type of lamination of 

 their own, somewhat different from that of any of the other sauropod 

 genera. The spines of the anterior dorsals are divided as in Apatosaurus 

 and Diplodocus, and the posterior dorsal spines are single, as in those 

 genera. There is a gradual transition from completely divided spines to 

 single spines, however, contrasting with the relatively abrupt change in 

 Apatosaurus. The spine of dorsal 7 is single or very slightly notched in 

 Camarasaurus, whereas in the column of Diplodocus the division persists, 

 to an appreciable extent, as far back as dorsal 9. 



The zygapophyses are large. In the anterior dorsal region they are far 



