758 . J. W. HULKE ON ORNITHOPSIS. 
from the same district in Colorado, defined the genera Camarasaurus 
and Amphicelias, the species of which, mostly of surpassing bulk, 
had precaudal vertebre laterally excavated by large internal cham- 
bers as in (Hueamerotus) Ornithopsis and Adlantostur US 
Last autumn (1878) Prof. Marsh and, later, Prof. Cope saw my 
fossils, and recognized their likeness to some of the new Colorado 
Dinosaurs. A closer comparison of Ornithopsis with these was 
desirable; and for my assistance in this task both these gentlemen 
forwarded me copies of all their published papers relating to them, 
for which, as also for much valuable information respecting them 
otherwise imparted to me, I here express my sincere thanks. 
Of the Colorado Dinosaurs whose vertebrae present correspondences 
with those of Ornithopsis the following genera have been de- 
fined :— 
Prof. O. O. Marsu. Prof. Corr. 
1. Titanosawrus = Atlantosaurus. 1. Camarasaurus. 
2. Morosaurus. 2. Amphicelias. 
3. Apatosaurus. 3. Hpanterias. 
4, Allosaurus. 
5. Diplodocus. 
Professor Marsh’s five genera form a natural group or suborder in 
Dinosauria, designated by him Sauropoda, distinguished by the 
principal characters of their feet, which are plantigrade and penta- 
dactyle, having their carpalia and tarsalia distinct. The fore and 
hind limbs are nearly equal in size. The precaudal vertebre are 
opisthoccelous ; their centra contain large cavities apparently pneu- 
matic. The sacral vertebra do not exceed four, and each supports 
its own transverse process’. 
The first of Professor Cope’s three genera, Camarasaurus, has been 
identified by him with Ailantosaurus of Marsh{; but this is dis- 
allowed by Prof. Marsh on the ground of the different construction 
of the sacral vertebrae, which Marsh finds in Adlantosaurus to have 
chambered centra, those of Camarasaurus being described by Prof. 
Cope as solid$. 
Of Camarasaurus, Prof. Cope writes :—‘“ The vertebree of the cer- 
vical, dorsal, and lumbar region are all opisthoccelous, 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 antero-posterior diameter.” 
‘The centra of the cervicals and dorsals are hollow, and the interior 
chambers communicate with the cavity (outer surface?) of the body 
by a large foramen on each side, which is below the base of the 
diapophysis. In the cervical vertebrae it is very elongate, and ex- 
tends between the base of the parapophysis and diapophysis. In 
* Prof. EH. D. Cope, Pal. Bulletin, No. 25, August 1877 (and Proc. Amer. 
Phil. Soc. same date); and Pal. Bulletin, No. 27, Dec. 1877. 
+ Principal characters of American Jurassic Dinosaurs, by Prof. O. C. Marsh, 
parts 1, 2 (1878-9). { American Naturalist, June 1878, p. 406. 
§ Pal. Bulletin, No. 28, p. 235, July 12, 1878. 
