Cope.] ^"^ [April 15, 



Measurements of Cranium. M. 



r anteropos- 



Diameter crown third permanent premolar -Z terior. . . .007 



( transverse. .005 



Anteroposterior diameter crown first premolar 0045 



(anteroposterior 010 



Diameters crown first true molar < ^ „^ nio 



(transverse 012 



( anteropos- 



Diameters crown second inferior true molar -< terior . Oil 



(^ transverse. .0075 



Diameter of root of inferior canine near crown 0035 



Vertebrae,. The atlas is about as long relatively as that of the horse. Its 

 transverse processes have more anteroposterior than transverse extent. 

 The summit of the neural arch has a median ridge separating two grooves. 

 The inferior surface of the centrum has a nearly median, obtuse hypa- 

 pophysis. The axial facets are well separated below. The vertebrarterial 

 canal pierces the base of the transverse process behind and below, and 

 notches it deeply anteriorly. Above this notch the usual perforation of the 

 arch is present. The axis is not relatively quite so long as that of the horse ; 

 it is a little longer than in HyracTiyus eximius, but rather shorter than in 

 Hyraeodon arcidens (PI. CII, Fig. 7). The atlantal facets are spread well 

 apart, and the articulating surface of the odontoid does not connect with 

 them. The latter is rather long, is obtuse, and slightly recurved ; it has 

 no raised borders. Between the atlantal faces the inferior surface is plane. 

 Posterior to this the middle line bears a prominent keel. The diapophyses 

 are long, narrow and recurved, and each is pierced at the base by the ver- 

 tebrarterial canal. The posterior articular face is but little concave, and a 

 little oblique, and is a little wider than long. 



The succeeding cervicals regularly diminish in length, and become more 

 strongly opisthoccelous, the seventh having quite a ball in front. The 

 sixth has a slender diapophysis directed posteriorly, and quite distinct from 

 the wide and long parapophysis which is directed downwards and out- 

 wards. The posterior angle of the latter extends as far back as the cen- 

 trum. The seventh has only a flat transverse diapophysis. The first 

 dorsal has a veiy stout diapophj^sis excavated below for the rib tubercle. 

 The diapophyses of the third and fourth dorsals are not so stout. The ca- 

 pitular fossae are large. The centra of the anterior dorsals are flattened 

 below ; they are concealed in part by the matrix in this specimen. The 

 neural spine of the sixth cervical is narrow, and is directed forwards. 

 That of the seventh is vertical, and narrows rapidly from a base which is 

 rather wide anteroposteriorly. The spines of the dorsals are wider, and 

 are directed gently posteriorly ; they are probably long, judging from the 



size of their bases. 



Measurements of Verteirce. M. 



Length centrum of atlas on side 027 



below 010 



Width " " " posteriorly 030 



