Cope. ] 234 [Dec. 21, 
terior limbs. The scapula is enormous as compared with the pelvic bones. 
The sacrum is also small and short, showing that the weight was not borne 
on the hinder limbs. The great length of the humerus in the probably 
allied genus Dystropheus, from the Trias of Utah, adds to the probability 
that the same bones were large in Camarasaurus. This character, taken 
in connection with the remarkably long neck possessed by that genus, 
suggests a resemblance in form and habits between those huge reptiles and 
the giraffe. While some of the later Dinosauria elevated themselves on 
their hind limbs to reach the tree-tops on which they fed, the general form 
of the body in some of these earlier types enabled them to reach their food 
without the anterior limbs leaving the earth. 
Another remarkable peculiarity which these genera share with Dystro- 
pheus and Cetiosaurus is the irregular and pitted character of the articular 
extremities of some of the bones. This indicates a cartilaginous covering, 
and probably in some instances an osseous Cap or epiplysis. 
Dr. Hayden visited the locality of Mr. Lucas’ excavations, and informs 
me that the formation from which the Camarasaurus was obtained, is the 
Dakota. Prof. Marsh has attempted to identify what is, according to Prof. 
Mudge, the same horizon, one hundred miles north of Canyon City, with 
the Wealden of England. Specimens from the northern locality which I 
have examined render it certain that the horizon is that of Mr. Lucas’ ex- 
cavations. Of this I may say that there is no paleontological evidence of 
its identity with the Wealden. The resemblance of the vertebrate fossils 
to those of the English Oolite is much greater, but not sufficient as yet for 
identification. 
The discovery of Vertebrata in the strata of the Dakota epoch is an im- 
portant addition to the geology and paleontology of North America. The 
numerous geologists who have explored its outcrops have failed hitherto 
to observe remains of this class of animals. Credit is due to Superintendent 
O. W. Lucas for this discovery, and also in an especial manner for the 
skill and care he has exercised in taking out and shipping the ponderous 
specimens. 
CAMARASAURUS Cope. 
Paleontological Bulletin No. 25, p. 5; (published August 23, 1877). 
The characters of this genus are derived from nearly all portions of the 
skeleton excepting the skull and ungues. The bones are generally in good 
preservation. 
The vertebre of the cervical, dorsal and lumbar region are all opistho- 
coelous or reversed ball and socket. The centra of the cervicals are very 
elongate, but those which follow them diminish rapidly in length, until in 
the lumbar region they have but a small anteroposterior diameter. The 
anterior caudal vertebre are also very short and wide; but the length of 
the centra gradually increases, so that the distal ones are quite elongate. 
The caudal centra are all moderately amphicoelous. 
The centra of the cervicals and dorsals are hollow, and the interior 
