Prof. O. C. Marsh—Restoration of Dionsaurs. 155. 
found in the upper Jurassic of Colorado. The associated fossils 
were mainly other dinosaurs, especially Sauropoda and Ornithopoda, 
together with various small mammals. 
Restoration of Claosaurus. (Plate VII.) 
The most interesting feature in the restoration of Claosaurus given 
on Plate VII. is the skull, which has been fully described by the 
writer elsewhere, but its main features may be noticed here. This. 
skull is long and narrow, with the facial portion especially produced. 
The anterior part is only moderately expanded transversely, thus 
differing from that of Hadrosaurus, a nearly allied form. Seen from 
the side, the skull of Claosaurus shows a blunt, rugose muzzle, 
formed above by the premaxillary, and below by the predentary,. 
both probably covered in life with a thick corneous integument. 
Behind the upper part of this muzzle is an enormous lateral 
cavity, which includes the narial orifice, but was evidently occupied 
in life mainly by a nasal gland, somewhat_like that in the existing 
Monitor, and also seen in some Birds. This cavity is bounded 
externally by the nasal bone and the premaxillary. The orbit is 
very large, and subtriangular in outline. It is formed above by the 
prefrontal, frontal, and postfrontal, and below mainly by the jugal. 
There are no supra-orbital bones. A distinct lachrymal forms a 
portion of the anterior border. The infra-temporal fossa is large, 
and bounded below by the jugal. There is a thin quadrato-jugal 
between the jugal and quadrate. The occipital condyle is directed 
backward and downward. 
The nasals are very long and slender, and in front are separated 
by the narrow superior processes of the premaxillaries. The frontals 
are short and broad, and somewhat concave above. The parietals 
are firmly codssified, and very small, forming a thin partition 
between the supra-temporal fosse. The latter are bounded pos- 
teriorly by the massive squamosals, which contain a deep cavity for 
the head of the quadrate, and also overlap the exoccipitals. 
The striking features of the lower jaw are the massive rugose 
predentary, the large and powerful dentary bone with its robust. 
coronoid process, and the very small angular and articular bones. 
The teeth are confined entirely to the maxillary and dentary 
bones. They closely resemble those of Hadrosaurus, are arranged 
in the same manner, and appear to be equally numerous. They 
were well adapted to a diet of soft succulent vegetation. 
The main characters of the vertebral column of Claosaurus are 
shown in the restoration. ‘There are thirty vertebree between the 
skull and sacrum, nine in the sacrum, and about sixty in the tail. 
The whole vertebral column was found in position except the 
terminal caudals, which are here represented in outline. The cervical 
vertebrae are strongly opisthoccelian, and the first eleven have short 
ribs. The dorsals are also opisthoccelian. There are no true lumbar 
vertebree, as the last of those in front of the sacrum support free 
1 American Journal of Science, vol. xxxix. p. 423, May, 1890; vol. xliii. p. 453, 
May, 1892; vol. xliv. p. 171, August, 1892; and vol. xliv. p. 344, October, 1892. 
