EOCENE CEOCODILIA. 
67 
Crocodilus Pliodon, Marsh. 
Plate xxxi, figs. 18-23. 
Amer. Journ. Sci. Arts, 1871, p. 454. 
Two individuals which agree with the description cited in the depressed 
form of the centra of the dorsal vertebras, the articulated dermal scuta, and 
general proportions, are not accompanied by cranial bones, excepting a por¬ 
tion of the parietal. This displays three larger or four smaller pits between 
the temporal fossae. The odontoid bone is elongate. The centrum of the 
axis is much compressed, and is strongly keeled on the median line below, 
being without lateral longitudinal angles. In an anterior cervical vertebra, 
the hypapophysis is connected by a lateral thickening with the parapophysis, 
while in a posterior cervical this connection is wanting. The centra of the 
lumbars are not compressed ; sacral centra depressed. 
The specimens are of rather small size, and one of them is adult. 
Parietal width. 0.015 
Parietal thickness. 0.010 
Width of end of quadrate condyle.-. 0. 025 
Thickness of the same. 0. 010 
Length of the axis, with odontoid. 0.040 
Length of dorsal.. .. 0. 029 
Width of dorsal cup.. 0.017 
Crocodilus chamensis, Cope. 
Plate xxxii, figs. 1-22. 
Eeport on vertebrate fossils ot New Mexico, U. S. Geog. Survs. W. of 100th M., 1874, 
p. 15 {Alligator), 
Represented by portions of the mandibular arch of a small Crocodilian, 
resembling in some respects the A. heterodon of the Wyoming beds. The 
posterior teeth have the same short, expanded, sessile, bean-shaped crowns, 
with a median longitudinal ridge, and more delicate lines radiating close 
together from it to the border of the crown. The anterior teeth differ in 
being cylindric instead of compressed. There is a large canine, preceded 
and followed by teeth of much smaller size. 
2Leasnrements. 
ir. 
Length of the symphysis. 0.019 
Length of the alveoli of six teeth from the symphysis... 0.022 
Width of the ramus just behind the symphysis. ... 0.010 
Long diameter of the posterior tooth. 0.005 
