38 MEMOIRS OF THE CARNEGIE MUSEUM 
The Caudals. (Plate I1., Series 5.) 
Only the seven anterior caudals are preserved in the type of the present species 
and these differ very little from the same vertebree in H. priscus, except that the 
transverse processes are less well developed and not so much expanded supero- 
inferiorly. Owing to the age of the individual the neural arches and transverse pro- 
cesses are not codssified with their respective centra although those of the first two 
are still held in place. The neural spines are short and stout and very rugose. 
That of the first is curved rather strongly backward. All the centra are very short 
and biconcave. The anterior zygapophyses are acutely wedge-shaped and extend 
well forward with the articular surfaces facing decidedly more inward than upward. 
The posterior zygapophyses are only flattened surfaces at the bases of the neural 
spines. The transverse processes are suturally connected both with the centra and 
the neural arches. 
The Vertebral Formula. 
From the foregoing descriptions of those portions of the vertebral column pre- 
served in the type of the present species and in that of H. priscws it will have become 
apparent that we must await future discoveries to determine with accuracy the 
vertebral formula of Haplocanthosawrus. The number of sacrals however may be 
considered as being definitely fixed at five, while the number of dorsals could not 
have been less than fourteen, thirteen of which are represented in the skeleton con- 
stituting the type of H. utterbacki. In this skeleton it would appear that only the 
first dorsal is missing, and fortunately that vertebra in the type of H- priscus was 
found interlocked by its zygapophyses with the last cervical. Although the various 
vertebree in the anterior dorsal region of the type of H. wtterbacki were for the most 
part found in such a scattered and disarticulated condition as to afford little direct 
evidence concerning the exact positions relative to one another which they occupied 
in the skeleton during the life of the animal, yet a close examination and careful 
study of the vertebrae has convinced me that there are no duplicates among the 
thirteen dorsals described and that there can be no question but that all of the thir- 
teen are dorsals and that they pertained to the skeleton of one and the same indi- 
vidual. That the first dorsal is wanting in this skeleton is shown by a careful com- 
parison of the neural arch and spine of the most anterior of this series with that of 
the known first dorsal in H. priscus, from which, as has been shown in the descrip- 
tions, it differs materially and in the direction of those characters which we should 
expect in the succeeding or second dorsal. For these reasons I have referred this 
spine to the second dorsal although the centrum which was found detached and 
separated, but which in the description and figure I have associated with this spine 
