31 



BATPvACHIA. 



SCAPHEBPETON, Cope. 

 SCAPHERPETON TECTUM, Cope. 

 Plate III, figs. 4-8. 

 Scapherpeton tectum, Cope. 1876. Proc. Aca(l. Nat. Sci. Philadel. vol. xxviii, p. 3.5.'i. 



This species is represented iu the collection by a number of trunk vertebras and 

 atlases. Almost as many of the latter as of the former were obtained, a peculiarity that 

 can be accounted for only by supposing that the stout, compact form of the atlas aided 

 in saving it from breakage. 



The trunk vertebi-ae, of which one of the best is figured, are biconcave, with well 

 developed pre- and postzygapophyses, a backwardly directed, stout neural spine whose 

 basal front extends forward as a prominent keel between the prezygapophyses. A number 

 of foramina enter the spine in its upper half where it is seen to be hollow. The centrum 

 is pinched or laterally compressed below, so as to produce a strong carination inferiorly, 

 and an elongation of the articular cups downward. The uotochord is not persistent ; 

 the foramince for its entry into the central body are conspicuous at the bottom of the 

 articular cups. The diapophysis is directed outward and backward and has an irregular, 

 figure 8 shaped, transverse section, as described by Cope. A foramen enters the base of 

 the diapophysis from in front, another from behind and, on the right side of the vertebra 

 figured, one also enters from below. In figure 4 the neural spine and the postzygapo- 

 physes are restored from a separate spine to the base of which the zygapophyses remain 

 attached. In one of the larger vertebrse, the roof of the neural canal is angularly 

 vaulted and the front border of the arch between the prezygapophyses is notched and 

 turned slightly upward. Numerous small foramina occur in all parts of the vertebrae. 



Three figures are given of one of the largest and best preserved atlases, to show the 

 two facets for articulation with the occipital condyles of the skull, the anterior process 

 projecting from the centrum between the two facets, and the articular cup behind. A 

 number of foramina occur in the concave inferior stirface of the atlas. Other foramina 

 occur as depicted. 



Measurements. 



Of trunk vertebra : M. 



Length of centrum ■ 008 



Height of articular cups , • 006 



Breadth of same " 004 



Diameter of notochordal foramen ■ 001 



Antero-posterior diameter of neural spine measured from between postzygapo- 

 physes , , ■ 0035 



Of atlas : 



Extreme length • 007 



Extreme breadth ■ 0095 



Height of facets for articulation with condyles of skull • 003 



Breadth of same • 004 



Height of articular cup • 0037 



Width of same ' • 003 



Belly River series. Red Deer river, 1901. 



