1878. ] Saurians of the Dakota Beds of Colorado. 8i 
in dimensions those of any known saurian, equaling those of the 
right whale. The centra measure sixteen inches in transverse 
diameter. The neck was probably ten feet in length. 
That this species was capable of and accustomed to progres- 
sion on land, is certain from the characters of the bones of the 
limbs and their supports above described. The extraordinary 
provision for lightening the weight of a portion of the skeleton 
has more than one significance. It must be borne in mind that 
the caudal vertebræ retain the solid character seen in those gen- 
era which stood habitually on their hind limbs. That the present 
species was herbivorous is suggested simply by its huge dimen- 
sions, and the natural difficulty of supplying itself with animal 
food. 
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 Dystrophæus, from the Trias of Utah, 
adds to the probability that the same bones were large in Cama- 
ràsaurus. This character, taken in connection with the remark- 
ably 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. 
The vertebra from all parts of the column of Camarasaurus are 
known, and those of the dorsal and lumbar regions present the 
extraordinary character, of which a trace is seen in Cetiosaurus, 
of neural spines expanded transversely to the axis of the column. 
_ Numerous vertebrz of Amphicelias are known, and in the dor- 
-sals in which the neural spine is preserved, the latter displays the 
usual form, that is, it is compressed in the direction of the axis of 
the column. The centra differ from those of Camarasaurus in 
the form of their articular extremities, resembling more nearly in 
_ this respect the genus Zichosteus Cope (Paleontological Bulletin, 
No. 26, p. 194). They are unequally amphiccelous, the posterior 
extremity being more concave, and with prominent margins; 
while the opposite one is less expanded, and is but slightly con- 
. cave, The neural arch is codéssified to the centrum, and there is 
no capitular costal articulation on the latter. 
