137 



terior zygapophyses. The inferior surfaces of the centra display a more or 

 less prominent longitudinal median ridge. 



Measurements. 



M. 



Length of the frontal bono to the naros . 0. 150 



Width of the frontal bono posteriorly 0. 140 



Width of tho frontal bone at the orbits 0. 104 



Width of the frontal bono at the nares 0.040 



Width of the palatine at the third tooth in front of the transverse process .*. 0. 037 



Width of the palatine just behind the transverse process - '. 0. 035 



Depth of the mandible at the cotylus 0.040 



Depth of the splenial condyle - 0. 032 



Width of the proximal articular surface of the quadrate (transverse) 0. 023 



Width of the distal articular surface 0.043 



Length of the third cervical centrum 0. 0G2 



Depth of the ball of tho third cervical centrum 0.030 



Width of the ball of the third cervical centrum 0.037 



Length of the articular end of the fixed hypapophysis 0.025 



Length of the free hypapophysis 0. 029 



Length of a median dorsal centrum 0. 072 



Width of tho ball of a median dorsal centrum 0. 048 



Depth of the ball of a median dorsal centrum 0. 040 



This species need only be compared with the Clidastes stenops, Cope, 

 which exhibits the same peculiarity of roof-shaped prefrontal bones. That 

 species has the cervical articular faces entirely round ; the frontal bone is 

 keeled in the middle, and the palatine much more vertically compressed. 

 The quadrate bone differs in various respects ; among others, in the round 

 form of the stapedial pit. As compared with the species described by Pro- 

 fessor Marsh as Edestosaurus dispar and E. velox, it differs in the form of the 

 quadrate, which, in these species, is much as in G. tortor and C. stenops; i. e., 

 with short proximal hook, oblique inferior articular surface, round pit, &c. 

 In this species, the quadrate is truncate distally, &c. This fine species was 

 discovered by the veteran geologist, Prof. B. F. Mudge, during his annual 

 expedition of 1873. 



AA. Centra of anterior dorsals compressed. 



Clidastes cineriakum, Cope. 



The largest species of this genus, as indicated by the zygosphen articu- 

 lation of the vertebrae. 



The region where it was found is the same as the last, but the speci- 

 mens were taken from the gray bed, perhaps the same that produced the 

 Eta, us platyurus, Cope. They consist of vertebras and pterygoid 



lb c 



