222 PATAGONIAN EXPEDITIONS I PALEONTOLOGY. 



No. No. No. No. No. No. 



I. 2. 15,597- 15,545- 15> l6 - 1 



Palate, width at 4 ........................ 013 .on .012 .012 .010 



" & ........................ oio .on .012 .011 .010 



Rostrum, width over 1 ................... .026 .030 .029 .030 



No. No. No. 



Mandible, length from condyle ............ .107 ?.ios 



" " " angle .............. -114 -"3 



" " of predentary beak ....... .026 .026 ? .026 



depth at s .................... .025 .024 .027 



" height of coronoid .............. ' .05 3 .051 



Vertebral Column, Ribs and Sternum. The vertebral column has the 

 following formula : C.y ; Th. 21-22 ; L. 3-4 ; S. 5-6 ; Cd 20. 



The atlas is relatively longer, higher and narrower than in H. longiceps 

 and the neural arch is separated from the posterior cotyles; the neural 

 canal is higher and narrower than in the latter species and the transverse 

 processes are smaller ; the internal branch of the vertebrarterial canal is 

 an open groove. The axis has a well-defined ventral keel, the facets for 

 the atlas rise higher upon the sides of the neural canal, but project less 

 below the centrum than in H. longiceps ; the odontoid process is rela- 

 tively long and slender ; the neural canal is high and narrow and the spine 

 is a hatchet-like plate, much more extended antero-posteriorly in some 

 individuals than in others. The third cervical has a short, broad, de- 

 pressed centrum, with indistinct ventral keel ; the neural arch is broad, 

 the canal relatively large and the spine is a low ridge ; the transverse 

 process, which is perforated by a short canal, does not project far out- 

 ward from the side of the centrum, but is much extended antero-poste- 

 riorly ; the pleurapophysial element is divided into nearly equal anterior 

 and posterior portions, of which the former is rather more slender and 

 pointed. The fourth cervical resembles the third, but has a slightly longer 

 and narrower centrum, smaller neural canal, and more distinct spine. In 

 the fifth, the spine is still more distinct and the anterior division of the trans- 

 verse process is considerably shortened. The sixth vertebra differs from 

 the fifth chiefly in the character of the transverse process, which is clearly 

 distinguished into diapophysial and pleurapophysial elements ; the latter 

 .is a large, compressed plate, which projects far below the level of the cen- 

 trum ; the neural arch is very narrow antero-posteriorly. The seventh 



