40 REVISION OF THE PELYCOSAURIA. 



C. collctti Cope. 



C. collet t i CoT^ft. Proc. Acad. Nat. Sc. Phila., 1875, p. 407. 

 Case, Jnl. Geol., vol. viii, 1900, p. 711. 



Type : Isolated vertebrte. Among others an atlas, an anterior dorsal, lumbars, 

 and caudals. No. 6530 University of Chicago, Gurley, coll.; from Vermilion county, 

 Illinois. Plate 7. 



Original description: "There is a shallow fossa in the entering angle between the 

 superior and inferior articular facets of the front of the axis, and the centrum of the 

 same is obtusely keeled below. The border of the anterior face of the dorsal vertebrae 

 with keeled centrum is undulate. The obtuse inferior face of another dorsal is rugu- 

 lose, and the edge of the face is not undulate. The inferior faces of the two caudals 

 are marked with fine parallel grooves, while in another caudal and the (?) sacrals the 

 same is smooth. There are some longitudinal ridges on the upper side of the larger 

 caudal." 



Measurements. 



m. m. 



Length, centrum of axis 0.006 Width, centrum, rounded dorsal, behind o.oio 



Width, centrum of axis at middle behind 008 Width, neural canal, behind 004 



Depth, centrum of axis (oblique) 010 Length, centrum, larger caudal .014 



Length, centrum of sharp-keeled dorsal 014 Width, centrum, larger caudal 008 



Depth, centrum of sharp-keeled dorsal, behind.. .012 Depth, centrum, larger caudal 008 



Width, centrum of sharp-keeled dorsal, behind-. .012 Length, smaller caudal 010 



Length, centrum, rounded dorsal 012 Depth, centrum, smaller caudal 007 



Depth, centrum, rounded dorsal, behind on Width, centrum, smaller caudal 007 



The vertebra described by Cope as tlie axis is the atlas (plate 7, figs. 9 

 and 10) and the vertebra with an "obtuse inferior face" is a posterior 

 dorsal or lumbar (plate 7, figs. 1-8). Other specimens regarded by Cope as 

 belonging to the species are Nos. 6531 and 657S University of Chicago. 



These vertebrse might be part of the same animal referred to as Clep- 

 sydrops peduncidatus, Dimetrodon obtusidens, or Elcabrosaunts baldwini. It 

 is indeterminate. 



Clepsydrops limbatus Cope. 



Proc. Am. Phil. Soc, vol. xvii, 1877, p. 193. Also Pal. Bull. 26, p. 196. 



Type: Several isolated vertebrse. One showing the character described has 

 been sawn apart longitudinally and vertically. No. 4144 Am. Mus. Nat. Hist., Cope, 

 coll.; from Texas. 



Original description : "As typical of the new species I select a vertebra, which 

 may be exactly compared with the corresponding one of C. coUetii. The centrum is 

 about as wide as long, and its sides are very concave, much more so than in C. col- 

 letii, and the rim-like borders of the articular extremities are connected by a straight 

 compressed hypophysial keel. The sides of the foramen cliorda- dorsalis are convex 

 in the longitudinal .section, thus contracting the opening, as compared with the very 

 wide flare of the border of one of the extremities of the centrum. This flare receives 

 the wide recurved border of the opposite extremity of the adjoining centrum, forming 

 a kind of ball and socket articulation. 



"This reflected surface forms a ridge with the funnel of the foramen at this 

 extremity of the vertebra. The concave extremity is produced downwards, so that 



