140 



of an anterior cervical is little, or not at all, distorted, as are also many of the 

 caudals. All the dorsals and cervicals have transversely-oval articular faces, 

 openly notched above for the neural canal. The fixed hypapophyses are 

 large; the last one small and subconic, abruptly following a large truncate 

 one. The three succeeding dorsals are keeled below, the Reel of the last 

 low and obtuse. The zygosphen is weak, and deeply notched in the middle. 

 On the anterior cervicals, it is rudimental; but, on the dorsals, supports a well- 

 developed articular facet, which meets a corresponding one of the zygantrum. 

 The fixed hypapophyses and roofs of the posterior zygapophyses are rugose, 

 with grooves and ridges. The articular faces of the caudals are broad, 

 vertical ovals as far as the specimens extend, the series including only a part 

 of those with diapophyses. On the anterior caudals, the chevron-facets are 

 compressed. The neural spines are thinned out in front; obtuse at the base 

 behind, but expanding to a thin edge there also. The sides are longitudinally 

 grooved. Diapophyses on the middles of the sides. Some ribs have the 

 heads not expandad but truncate. The angle of the mandible is produced 

 backward, and below the plane of the lower margin of the ramus, in a marked 

 manner. The lower margin and the surface next the smooth edge are 



rugose. 



Measurements. 



M. 



Depth of tku inaudible at the posterior margin of the cotylus 0. 058 



Length of the centrum of the anterior cervical 0.070 



Diameter of the ball, vortical 0. 02S 



Diameter of the ball, transverse 0.040 



Expanse of the diapophyses of the anterior cervical 0. 095 



Expanse of the anterior sygapophyses 0. 064 



Expanse of the diapophyses of the anterior dorsal 0. 115 



Length of the centrum of the anterior dorsal 0.071 



Length of the centrum of the anterior caudal 0.053 



Depth of the cup of the anterior caudal : 0. 014 



Width of the cup of the anterior caudal 0. 041 



Width of the neural spine 0. o:j:j 



Elevation of the neural spine (apex lost) 0.070 



Diameter of the centrum of the twenty-fourth caudal, vertical 0.039 



Diameter of the centrum of the twenty-fourth caudal, transverse 0.010 



Length of the centrum of the twenty-fourth caudal 0. 042 



This .species appears to have had proportions not unlike those of Plate- 

 carpus coryphceus; the specimen described being larger than that on which the 

 latter was based. It is also rather larger than the Clidastes planifrons, Cope, 

 the largesl of its genus, bul which, since its caudal vertebrae are unknown, may 

 yel be found to be a N It differs specifically from the S. anguliferus 



in ihe less development of the zygosphen. especially ou i he anterior vertebrae, 



