HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 283 
rather defective. The anterior face of the centrum was lost and has been restored. 
The extremities of both transverse processes were more or less mutilated and the 
upper end of the dorsal spine was gone. No. 1712 (see Fig. 43) is a practically 
perfect specimen, somewhat smaller than No. 1604. With its well-preserved 
surfaces before him, Mr. Peterson has been able to repair specimen No. 1604 in an 
excellent manner. No. 1713 has lost the epiphyses of the centrum and is badly 
crushed and distorted about the neural arch. 
The spine of the fifth dorsal is somewhat shorter than that of the preceding 
vertebra, and in horizontal cross-section at its origin is almost equilaterally tri- 
angular. It preserves almost the same antero-posterior diameter from the base 
to the extremity, though at the tip it is, as all of the dorsal vertebree, somewhat 
swollen to form ligamentary attachments. The transverse processes have a 
rather well defined mammillary projection the transverse diameter of which is 
fully twice that of the antero-posterior dimension. The articulating face for the 
tubercle of the rib is separated from the mammillary by a shallow constriction, 
deeper below than above, and looks outward and slightly forward. The prezy- 
gapophyses are relatively small, look upward and slightly forward. The post- 
zygapophyses are quite small and look downward and somewhat inward. The 
upper margin of the centrum on its outer fourth rolls upward more than in the 
fourth dorsal to assist in forming the back wall of the exit for the spinal nerve. 
The anterior and posterior articulating faces of the centrum are vertical in position, 
the former slightly convex, the latter slightly concave, as is the case in the pre- 
ceding and succeeding vertebre. In specimen No. 1604 there is in the posterior 
face of the transverse process a transversely longitudinal depression already indi- 
cating the commencement of the formation of the shaft of the metapophysis. 
This does not appear in specimen No. 1712. It is reproduced, however, in suc- 
ceeding vertebrz, as will be shown. 
MEASUREMENTS OF Firra Dorsau VERTEBRA.” 
1604 1712 1713 
mm mm mm 
Greatest height from base of centrum to top of spine........................ 285 283 255 
Greatest transverse diameter measured across transverse processes............ 154 130 120 
Greatest antero-posterior diametey measured from front of prezygapophyses to 
back of postzygapophyses..... Bate ey SNES HUA PON Sica ease lho Lon Ae 72 58 68 
Length of centrum along floor of neural canal.............. ...........000- 47 42 38 
Wensthyomcentrumyaloneyinieronsuniace wanna in a eae ee aes on. 40 38 80 
Vertical diameter of anterior face of centrum.....................0+..00000% 50 44 43 
Mransverse diameter of anterior face of centrum.........................-.. 46 44 45 
7 All numbers in italics denote approximate measurements, the specimens being broken or restored. 
