1878.] Oiy [Cope. 



Measurements. M. 



Length of a centrum with an intercentrum attached 0056 



Length of centrum 0040 



vertical 0035 



{ 



Diameter of centrum , 



horizontal 0035 



Expanse of diapophyses 0080 



" heads of rib 0035 



Elevation to summit of neural canal 0045 



Comparison with the vertebrae which I have found associated with the 

 jaws and teeth of Bolosaurus striatus reveals the following differences: 

 The neural arches of the latter are distinct ; the intercentra are not present 

 on the vertebrae observed (five in one series and five in another) ; and the 

 centra are compressed with inferior rib. There are no capitular articular- 

 facets in the vertebrae of Bolosaurus described. 



Theropleura retroversa. Gen. et spec. nov. 



Char. Gen. Rhynchocephalian reptiles with free neural arch, and a 

 capitular costal articulation on the centrum ; the intercentrum probably, 

 and the hyposphen certainly, wanting. 



This genus is similar to Lysorophus in its free neural arch, but there is 

 no capitular costal articulation on the known vertebrae of that genus. The 

 small costal face of the diapophyses is distinct from what is seen in Epicor- 

 dylus and Empedocles. 



Char. Specif. Size medium, or rather larger than that of Clepsy drops 

 natalis. A. number of small vertebrae may belong to a young individual, 

 but I regard as type a dorsal vertebra of an adult, where the suture of the 

 neural arch is visible but adherent. The species is characterized by the 

 wide posterior expansion of the border of the articular face of the centrum, 

 forming the capitular facet for the rib. It approaches near to the dia- 

 pophysis, and descends to the basal fourth of the centrum. There is an 

 angular ridge passing backwards from the inferior border of the diapophy- 

 sis to the border of the articular face. Below this angle and behind the 

 capitular costal face the centrum is deeply concave, the concavities of the 

 opposite sides being separated below on the median line by a narrow ob- 

 tuse keel. The centrum is as deep and long as wide. 



Measurements. M. 



( antero-posterior 025 



Diameter of centrum -c vertical 025 



(_ transverse 025 



The small specimens agree with the large one in the strong, longitudinal 

 angle connecting the diapophysis with the posterior border of the centrum, 

 and in the wide capitular articular surface. 



Theropleura uniformis. Sp. nov. 

 This species is represented by the vertebrae of two individvals, and per- 

 haps of two others of smaller size. The dorsal centra are characterized by 



* Proceedings Amer. Philos. Soc, 1877, p. 187. 



