56 FIELD CoLuMBIAN MuskuM—GEOoLocy, VoL. II. 
sutures separating the angular, surangular and dentary are shown in 
the figure. 
CERVICAL VERTEBR@.—There were twenty-eight cervical vertebra 
in a continuous series preserved, the last five or six, owing to 
exposure, in a less perfect condition; the others complete or nearly 
so. Traces of the sutures uniting the neural arches with the centra 
can be observed in the third and fourth vertebrae only. The atlas and 
axis are so wedged in the compressed occipital region that the former 
bone can not be distinguished, and the latter is visible in part only. 
The third vertebre, herewith figured, differs from the following ones 
in the greater obliquity of the spine, in the more oblique anterior 
face of the centrum, in the presence of a conspicuous carina below in 
front, and in the simple, pointed shape of the single-headed rib. The 
fourth vertebre has the neural process less oblique and broader, the 
carina in the middle of the concavity of the under surface not visible 
from the side; the rib is broad and of nearly equal width throughout. 
In the sixth vertebra and beyond the neural process is broader and 
nearly vertical; the ribs are broad, with more marked anterior and 
posterior prolongations distally. The spines increase in width through- 
out the series, but are only a little longer posteriorly. The posterior 
centrum is more than three times the length of the anterior ones and 
the diameter posteriorly is more than twice that anteriorly. The ribs 
of the posterior vertebre are but little longer, though much wider, 
than those of the anterior vertebre. The following measurements 
will exhibit these differences in size more exactly: 





NUMBER OF VERTEBRA. 3 4 Cuero I4 | 20 ae 
Length oftcentrumss¢ oo mee cae 23 30 48 53 63 78 | fore) 
Heiwht.of centrum: (se. ‘ 25 27 | 42 44 50 | 60 | 68 - 
Height of spine above floor | | | 
of neuraliGanale ys” WP are 46 a7 | 47 50 | 62 
Widthof spine 35". 59") Ve a ee cee 36 40 42 | 65 
Bengt otrrnin i caese he es hel ees Orie at 40 48 eee. 





Width of tiby. 5° BR eae. | aoe aon 

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