Petp:rson : ()sTEoi,(^c;\' ok Oxvdacivlus. 451 



Dorsals Tico to Twelve. — As before stated, there is a break in the 

 vertebral column of the type specimen, between dorsals one and five, 

 three vertebrse being entirely absent. From other material (No. 

 562) it is evident that the second dorsal has a shorter centrum than 

 the first, as in the camel, while in the llama the two are about equal. 

 It appears that the median ridge on the inferior face of the centrum is 

 well marked, but the pits referred to in describing the first dorsal are 

 nearly obsolete. From the material at hand it is obvious that the 

 spine is higher and narrower than that on the first dorsal, and that it 

 increases in height until the fifth vertebra is reached, and in width 

 until the sixth, which also seems to be true in the recent forms. The 

 third and fourth vertebrae are apparently very similar to the second. 

 The posterior part of the centrum of the fifth dorsal is present in the 

 type and was found in position with the two succeeding vertebrae 

 which were interlocked by their zygapophyses when found. The 

 centra of these two vertebrae (sixth and seventh) are more laterally 

 compressed, and somewhat higher proportionally than are those of 

 the preceding dorsals. The neural canal is moderately large. The 

 transverse processes are comparatively heavy, and the zygapophyses 

 have that peculiar continuous articulation from side to side referred to 

 in the description of the first dorsal. The ninth and tenth dorsals 

 are complete including the neural spines and present characters simi- 

 lar to that of the sixth and seventh. The transverse processes on the 

 ninth and tenth dorsals are greatly reduced. The neural spines are 

 broad and thin. The spine on the tenth dorsal is slightly recurved 

 superiorly, in anticipation of the erect spine of the anticlinal or 

 twelfth vertebra. The postzygapophysis on the tenth dorsal has a 

 small groove separating the articulating facets while the prezygapoph- 

 yses of the ninth indicate a continuous facet. The eleventh and 

 twelfth dorsals are missing in the type. 



The Lumbar Vertebra. — In the type of this genus the three ante- 

 rior lumbars are missing. The four vertebrae present were found 

 interlocked by their zygapophyses and also attached to the sacrum. 

 In skeleton Xo. 562 the first four lumbar vertebne have their centra 

 of equal length, while the centra of the following vertebrae become 

 shorter, the last being the shortest, broadest, and most depressed in 

 the series. The lumbars present in the type show less development 

 of the inferior keels than is shown in the recent camel and the 

 llama, and differ from the latter genera by having strong lateral 



