34 



Clidastes pumilus, Marsb, loe. cit. 

 Mobrara Cretaceous of the Smoky Hill River. 



A A. Centra of dorsal vertebrtie compressed : 



Clidastes oiNEriiATtU-M, Cope, Proceed. Amsr. Philosopliical Soc.,, 

 1870, 583. 



Mobrara Cretaceous of the Smoky Hill. 



SIEOXECTES, Cope. 



The characters of this genus are such as to unite closely that which 

 precedes it with that which follows in the present enumeration. It is 

 more nearly allied to Flatecarpus in the only species known, where the 

 zygosphen is weak, but articulates with special facets on the lateral 

 walls of the zygantrum. The form of the bones of the limbs is un- 

 known. 



SiRONECTES, ANGULIFERUS. 8p nov. 



Established on a portion of the left mandible, with a series of thirty 

 one vertebrae of a single individual discovered by Prof. B. F. Mudge in 

 the gray calcareous shale of Trego County, Kansas. 



Some of the vertebrse. have suffered from pressure, but the centrum 

 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 fol- 

 lowing a large truncate one. The three succeeding dorsals are keeled 

 below; the keel 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 com- 

 pressed. The neural spines are thinned out in front, obtuse at the base 

 behind, but expanding to a thin edge above it; the sides longitudinally 

 grooved. Diapophyses on the middles of the sides of the centra. Some 

 ribs have the heads not expanded but truncate. The angle of the man- 

 dible 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 mandible at posterior margin of cotylus 0.05S 



Length of centrum of anterior cervical 070 



-rs,. , J? ^1 1 11 ( vertical 028 



Diameter of the ball, | ^^^^^^^^^^ 040 



Expanse of diapophyses of ball 095 



Expanse of anterior zygapophyses .064 



Expanse of diapophyses of anterior dorsal 115 



Length of centrum of anterior dorsal 071 



