2 MEMOIRS OF THE CARNEGIE MUSEUM 
iS) 
which it agrees very well when compared with the spine of that vertebra in 
H. priscus where there can be no question as to the proper position relative to the 
dorsals. Moreover if the spine of the fourteenth cervical in H. priscus be interposed 
between the present spine and that of the thirteenth cervical in the present skeleton 
they are seen to form a well-graduated series leaving little doubt that the positions 
assigned to the various vertebree of this region of the cervical series in the skeleton 
under consideration are correct. The neural spine is faintly emarginate at the apex. 
The depth of the emargination is 4 mm. 
The Dorsals. (Plate II., Series 1 and 2.) 
The Second Dorsal (Plate II., Fig. 2, series 2.) There is in the vertebral series of 
the present skeleton no vertebra corresponding to the first dorsal in H. priscus. 
That vertebra is apparently unrepresented in the present series. The neural arch 
and spine found at 11’ fits fairly well on the centrum found at 11 and I have con- 
sidered them as pertaining to the second dorsal. As to the neural spine and arch 
there can be little doubt as to this determination, but as to the position of the cen- 
trum, it is by no means certain that it does not pertain to the first rather than the 
second dorsal. Indeed as regards the length and form of the centrum, character of 
the pleurocentral cavities, and position of the capitular rib facet, it would appear to 
more properly pertain to the first dorsal than to the second, while the widely separ- 
ated position (about four feet) in which they (the centra and neural arch) were 
found might be taken as an indication that they pertain to different vertebre. I 
have associated this centrum and spine in the same vertebra for no other reason 
than that when adjusted to one another they seem to agree fairly well. I believe 
it quite possible, even probable, that the centrum pertains to the first dorsal. As 
regards the neural arch and spine however, after comparing them with those of the 
first dorsal in H. priscus, there can be no reasonable doubt but that they pertain 
to the second dorsal. This position is indicated by the character of the anterior 
branch of the horizontal lamina which is much less modified to give support to the 
scapula than in the first dorsal of H. priscus. The articular surfaces of the post- 
zygapophyses have assumed a more perpendicular position in anticipation of the 
hyposphene-hypantrum method of articulation that obtains in the median and 
posterior dorsals. The neural spine is passing from the widely expanded scoop-lhke 
element seen in the posterior cervicals and dorsal one to the simpler form character- 
istic of the median and posterior dorsals. The superior branches of the postzygapo- 
physial lamina continue, however, confluent with the neural spine, extending to its 
very apex and enclosing laterally a rather deep cavity which, nevertheless, is much 
