12 MEMOIRS OF THE CARNEGIE MUSEUM 
Plate I., Fig. 6, second column, and a little anterior to this is a second lamina ai, 
which may be an anterior branch of the superior blade of the diapophysial lamina, 
but which is interpreted as a branch of the prespinal. 
Although the transverse process appears massive it is really very light and thin, 
and save toward the base it is made up entirely of the anterior blade of the hori- 
zontal lamina and the oblique lamina. ‘These two laminz meet at nearly right 
angles so as to enclose a very deep trough which opens downward, forward and 
outward and is confluent with the very deep infradiapophysial cavity. There is no 
prediapophysial cavity and the postdiapophysial cayity is very shallow and incon- 
spicuous. 
Seen from in front, the neural arch appears high and constricted just beneath 
the capitular rib facets but expanded in the region of the superior border of those 
surfaces. The anterior zygapophyses are elevated and have the articular surfaces 
elongated transversely and abbreviated antero-posteriorly. Beneath the anterior 
zygapophyses there is a deep infraprezygapophysial cavity confluent with a deep 
trough into which the neural canal opens. The supraprezygapophysial cavity is 
shallow and separated from the one below by a short, stout, transverse plate which 
gives support superiorly to the lateral borders of the neural arch. In cross-section 
the neural spine is triangular with the apex of the triangle directed forward and 
forming the rather broad and rugose prespinal surface. 
Seen from behind, the neural spine is broad and rugose, though much narrower 
than in the first dorsal. This is due to the greater development of the superior 
blades of the postzygapophysial lamine, which are thin and expanded and con- 
tinue to the summit of the neural spine. There are shallow supra- and infrazyga- 
pophysial cavities and the latter is much elongated and inclosed laterally by the 
inferior blades of the postzygapophysial laminze. These give support inferiorly to 
a well-formed hyposphenal process developed on this and the succeeding dorsals 
showing that in addition to the ordinary zygapophysial articulation of the preced- 
ing vertebree the dorsals of this region had a hyposphene-hypantrum articulation. 
Dorsals Seven? to Fourteen? Inclusive (Plate I., Figs. 7-14).— After the above 
rather tedious detailed description of the posterior cervicals and dorsals one and six?, 
the succeeding dorsals may best be described together. Since, in their more impor- 
tant and general characters, they agree very well both with one another and with 
the supposed sixth dorsal just described, the following description may very well be 
limited to a general reference to those characters wherein they all agree, followed by 
a special reference to the more important distinctive characters of each, wherever 
such exist. As already stated, these vertebrae, together with the one last described 
