7M E. C. CASE 



sides of the centrum are concave, and the inferior portion forms a prominent 

 rounded rib." 



MEASUREMENTS. 



C antero-posterior - - .oi6 m 



" Diameter of centrum < transverse - - - .015 



( vertical - - - - .016 " 



[Nos. 6534 (type s'pecimen) and 6535.] 



Clepsydrops vinslovii Cope. Plate II, Figs, ja, jb, jc, jd. 



Clepsydrops vinslovii Cope, 1877, Proc. Am. Phil. Soc., p. 62. 



This species was based on a single cervical vertebra with which others 

 were uncertainly identified. The specific characters given are as follows: 

 " The inferior median line is a keel ; some distance above it, the sides of the 

 centrum are full, rising in a longitudinal angle. There is no constriction or 

 fossa below the diapophysis as in C. colletti. The latter is anterior in posi- 

 tion, is vertically compressed, and is curved forward for a short distance 

 below. The posterior articular face is regularly funnel-shaped from the 

 margin ; the anterior face has a broad recurved lip. This passes around the 

 inferior margin, which is not projected forwards as in C. colletti. The zyga- 

 pophyses are well developed, and stand close together. The neural spine 

 is compressed, and the basal portion points somewhat forwards." 



MEASUREMENTS. 



" Length of centrum - - - - - - .01 i m 



Diameter of posterior articular face \ t 



r / transverse - .009 



Vertical diameter of diapophysis ... .006 



Expanse of posterior zygapophysis ... .009 



Antero-posterior diameter of base of neural spine .005 



Transverse diameter of neural arch ... .006 " 



[Nos. 6532 (type specimen) and 6533.] 



Lysorophus tricarinatus Cope. Plate II, Figs. I2<?, \2b, 12c. 



Lysorophus tricarinatus Cope, 1877, Proc. Am. Phil. Soc, p. 

 187. (Pal. Bull., No. 26.) 



The type specimens consist of two vertebras and a portion of a third. 

 The generic characters given by Cope are as follows : "Vertebras amphicoe- 

 lian, perforated by the foramen chordae dorsalis. Neural arch freely articu- 

 lated to the centrum. Floor of neural canal deeply excavated. No processes 

 or costal articulations on the centrum, which is excavated by longitudinal 

 fossae. Centrum not shortened." Specific characters : " Two centra and a 

 portion of a third represent this species. The former are a little longer than 

 wide and a little depressed. The facet for the neural arch is an elongate 

 plane truncating the border of the fossa of the neural canal on each side, 



