84 Saurians of the Dakota Beds of Colorado. (February, 
cave than those of the Camarasaurus supremus; and also differ in 
their relatively and absolutely greater breadth of body. 
The femur is extraordinarily robust. The great trochanter is 
low, but the shaft is widest where it expands outward. ‘The third 
trochanter is a ridge, is above the middle, and is short and little 
prominent. It is on the inner edge of the posterior aspect of the 
shaft, and looks backwards and inwards. The shaft in its present 
_ state is compressed so as to reduce the antero-posterior diameter. 
It is not however crushed or cracked. The condyles have much 
greater transverse than antero-posterior extent. They are mod- 
erately produced backward, and are separated by a deep pop- 
liteal groove, while the anterior trochlear groove is wide and 
well marked. The inner condyle is narrowed posteriorly, while 
the external one is obtuse and robust. Their articular faces are 
marked with irregular pits as in Dystropheus and Cetiosaurus. 
The length of this bone is fifty inches and the thickness four- 
teen inches. The body of the caudal vertebra is ten inches in 
transverse diameter. 
The character of the articular surfaces of the bones of the 
limbs already mentioned is a peculiarity of Camarasaurus as well 
as of the genera named. It indicates a thick cartilaginous cap 
of the bones, which, if ossified, would be an epiphysis like that 
of the Mammalia. I first observed this character in the Dys- — 
tropheus viemale, a huge saurian discovered by Prof. J. S. New- 
berry in the red rocks of the Painted Canyon, near the Sierra La 
Sal, in south-eastern Utah, and described by myself in Lieut 
Wheeler’s final report. The bed from which it was derived is 
supposed to be of Triassic or Jurassic age. It had an enormous i 
scapula like Camarasaurus, and a long straight humerus; its toes 
were short. It was probably a predecessor of the gigantic forms 
from the Dakota formation, and an inhabitant of a more ancient 
continent. It did not reach the dimensions of either of the species — 
of the genus above-named, or of Amphicelias, having been only 
as large as an elephant. eo 
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3 
- The genus Tickosteus included a species not larger than an 
‘alligator. Its vertebræ were hollow, but the internal chamber 
did not communicate with the body cavity. The only known 
species of Symphyrophus was of similar size, but the vertebral — 
__. bodies were solid. Some of the numerous crocodile-like teeth 
_ found by Mr. Lucas probably belong to species of these genera 
