152 EXTINCT VERTEBRATA FROM THE JUDITH RIVER 
half an inch. Robust transverse processes broken off in the specimens, projected from the 
conjunction of the vertebral arch and body. The spinal canal, retained entire in the — 
smaller specimen, is circular and one inch in diameter. 
The smaller caudal vertebral body, (figs. 6, 7,) has its anterior surface nearly plain or 
slightly depressed, while its posterior surface is moderately concave. Its length is about 
equal to its height, which is 2 inches, while its breadth is 24 inches. 
The first ungual phalanx, (figs. 4, 5,) resembles the corresponding bones of Jguanodon 
and Hadrosaurus. It is 5 inches long; 42 wide at base, by 32 thick; and 4 inches wide 
at the distal end, by 2% thick. Deep concavities exist each side of the distal extremity 
for the attachment of lateral ligaments. The proximal articular surface is a transverse 
reniform concavity; the distal articulation a transverse convexity slightly depressed to- 
wards its middle. 
Had the bones of Thespesius been found in association with the remains of Z’rachodon 
or Deinodon, or in the same geological formation, I would have suspected that they be- 
longed to one of the latter. 
Explanation of Figures, Plate 10. 
Figures 1—7. Vertebra and phalanx of THESPESIUS OCCIDENTALIS; one half the diameter of nature. 
Figure 1. Lateral view of an anterior caudal vertebra. 
Figure 2. Anterior view of same specimen as the last one. 
Figure 8. Ventral view of same specimen, exhibiting the articular processes of the chevron bones. 
Figure 4. Upper view of a first phalangial bone. 
Figure 5. Lateral view of the same. 
Figure 6. Lateral view of a posterior caudal vertebral body. 
Figure 7. Posterior view of the same specimen. 
CHELONIA. 
COMPSEMYS VICTUS. 
The above name is proposed for a species of turtle, indicated by several fragments of a 
carapace, obtained by Dr. Hayden, from the Great Lignite Tertiary Basin, near Long Lake, 
Nebraska. The more characteristic specimens consist of a vertebral plate, and the greater 
portions of the fifth and last right costal plates. 
The vertebral plate, (fig. 5, plate 11,) is about an inch in its antero-posterior and trans- 
verse diameters. The fifth costal plate, (figs. 6, 7, plate 11,) is much arched, is an 
inch and a quarter wide, two lines thick, and when perfect, appears to have been about 
four inches long. The fragment of a last costal plate is three lines thick. 
Marks upon the fifth costal plate, of the fourth and fifth vertebral scutes, indicate these 
to have been about two inches in width. 
The peculiarity of the specimens which has led to the proposal of the genus, consists in 
