36 



UNITED STATES NATIONAL MUSEUM BULLETIN 294 

 Table 22. — Measurements {in mm.) of the caudal vertebrae, USNM S36S6 



Anteroposterior diameter of centrum 

 Transverse diameter of centrum, anteriorly 

 N'ertical diameter of centrum, anteriorly 

 Minimum anteroposterior length of pedicle 



of neural arch 

 Transverse diameter of neural canal, anteriorly 

 \'ertical diameter of neural canal, anteriorly 

 Distance between ends of transverse processes 

 Dorsal edge of metapophysis to ventral face 



of centrum, anteriorly 

 Tip of neural spine to ventral face of centrum 



posteriorly 

 Transverse diameter of centrum, posteriorly 

 X'ertical diameter of centrum, posteriorly 



165 173 170 165 165 145 131 114 



280 248 299 186 138 136 



125 120 120 121 121 108 103 95 



123 119 118 118 117 114 107 102 



87 



87 



78 

 72 



72 

 62 



61 



48 



or diameter, 69 mm.), expanded distally and abruptly 

 truncated, dorsoventrally, flattened, and directed out- 

 ward and slightly forward. The neural canal, (pi. 25, 

 fig. 1) is narrow (19 mm.) anteriorly, and also reduced 

 in height (20 mm.). The outer half of the right trans- 

 verse process is broken off. The thin pedicles of the 

 neural arch have increased in length (76 mm.), but de- 

 creased in height. The low, but long (88 mm.) meta- 

 pophyses are directed more outward than upward (dis- 

 tance between dorsoexternal edges, 92 mm.) and rise 

 53 mm. above the floor of the neural canal. 



Second caudal. — The paired posterior haemal tuber- 

 cles are not strongly developed on the \'entral face of 

 the centrum and are, however, separated by a broad 

 shallow open groove or channel for tlie caudal artery. 

 The anterior haemapophyses are slightly developed. The 

 transverse processes are noticeably widened distally and 

 irregularly truncated; the anterior and posterior edges 

 of the.se processes are thin (minimum anteroposterior 

 diameter, 70 mm.). 



The lateral surfaces of the centrum (pi. 23, fig. 2) 

 above and below the transverse processes are deeply hol- 

 lowed out, and tlie posterior end is slightly more convex 

 than the more flattened anterior end. The transverse and 

 vertical diameters of the neural canal (pi. 25, fig. 2) 

 are reduced. The pedicles of the neural arch (length, 

 68 mm.) support the large metapophyses (length dorso- 

 external edge of right, 86 mm.) which are more up- 

 turned distally than those of the first caudal, and ri.se 

 58 mm. above the dorsal rim of anterior epiphysis; the 

 distance between the dorsoexternal edges is 107 mm. 



The neural spine (pi. 24, fig. 2) has decreased in 

 width and height, but rises 108 nun. above the roof of 

 the neural canal; this spine is obliquely truncated 

 distally. 



Third caudal. — This caudal is characterized by elon- 

 gate transvei-sely compressed posterior haemal tuber- 

 cules, separated by a deep open groove or channel for the 

 caudal artery, and rather small, low anterior haemal 

 tubercules. The sides of the centrum, both above and 

 below the transverse processes are deeply hollowed out, 

 and the posterior end of the centrum is slightly more 

 convex than the anterior end. As compared to those of 

 the second caudal, the transverse processes (pi. 24, fig. 



3) are shorter, more noticeably expanded distally and 

 abruptly truncated (minimum anteroposterior diam- 

 eter, 70 mm.). The neural canal is narrow and rather 

 long. 



The pedicles of the neural arch (length, 66 mm.) sup- 

 port large metapophyses (length dorsoexternal edge of 

 left, 78 mm.) which are strongly upturned distally, and 

 rise 58 mm. above the dorsal rim of anterior epiphysis; 

 the distance between the opposite dorsoexternal edges is 

 111 mm. 



The neural spine (pi. 23, fig. 3) has decreased notice- 

 ably in height, but rises 82 mm. above the roof of the 

 neural canal and is obliquely truncated distally. Tlie 

 reduction of the neural canal is continued. 



Fourth caudal. — The relatively long, laterally com- 

 pressed pair of jx)st«rior haemal tubercules are sep- 

 arated by a deep oj^en groove or channel for the caudal 

 artery. The anterior pair of haemal tubercules are rather 

 tliick and less elongated. The lateral surfaces of the 

 centinmi are deei)ly hollowed out, both above and below 

 the transverse ])rocesses. Both ends of the centrum are 

 somewhat convex. The transverse processes (pi. 24, fig. 



4) are shortened, obliquely truncated distally (mini- 

 mum anteroiK>steri<>r diameter, 69 mm.), and directed 

 outward and slightly foi-ward. Neither process is per- 

 forated. 



