42 REVISION OF THE PELYCOSAURIA. 



an anchylosed rib witli the distal broken portion inclined forward, as is 

 characteristic of the anterior caudal ribs of the Rhynchocephalia. 



This is an anterior caudal and is indeterminate. 



Another specimen regarded by Cope as belonging to the species is 

 No. 6535 University of Chicago. 



Clepsydrops vinslovii Cope. 



Cope, Proc. Am. Phil. Soc, vol. xvii, 1877, p. 61. 

 Case, Jnl. Geol., 1900, vol. viii, p. 714. 



Type: A single cervical with other vertebne doubtfully associated. No. 6532 

 University of Chicago, Gurley, coll.; from Vermilion county, Illinois (plate 7, figs. 

 16 and 17). 



Original description : "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. colletii. The latter is anterior in 

 position, 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. colletii. The zygapophyses are well-developed and stand 

 close together. The neural spine is compressed, and the basal portion points some- 

 what forwards." 



Measuremcyits. 



}».. m. 



Length of centrum o.oii Vertical diameter of diapophysis 0.006 



Diameter of posterior articular face: Expanse of posterior zygapophysis 009 



Vertical oog Antero-posterior diameter of base of neural spine .005 



Transverse oog Transverse diameter of neural arch 006 



These are the smallest vertebrae referred by Cope to this genus. They 

 might be the atlas and anterior cervicals of a small Clepsydrops natalis. 

 The species is indeterminate. 



Another specimen referred to the same species by Cope is No. 6533 

 University of Chicago. 



Clepsydrops natalis Cope. 



Proc. Am. Phil. Soc, vol. xvii, 1S7S, pp. 509 and 529. 



Type: This is the homeotype of the genus Clepsydrops. See description, p. 37. 

 No. 41 10 Am. Mus. Nat. Hist, Cope, coll.; from Texas. 



Original description: "The muzzle of this species is compressed and descends 

 obtusely at the ends as Bolosaurus striatus. The nostril and orbit are quite large. 

 The first premaxillary tooth is the largest and has a silky striation of the enamel ; its 

 crown is much less than that of the canine. The canine originates below a point a 

 short distance posterior to the nostril. 



Measiiremcnls. 



m. m. 



Length of skull posterior to base of quadrate-. .0.124 Length of crown of canine tooth 0.016 



Diameter of nostril 019 Antero-posterior diameter of canine tooth 005 



Depth of zygoma at orbit .012 



