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UNITED STATES NATIONAL MUSEUM BULLETIN 294 



neural arch extend most of the length of the centrum. 

 Both transvei-se processes (pi. 13, fig. 1), which lack 

 their extremities, were obviously shorter than those of 

 the twelfth lumbar. The neural canal (pi. 12, fig. 1) is 

 quite narrow. Posteriorly on the right side, commencing 

 at the level of the transverse process and extending up- 

 ward to the neural arch, a very large bony excrescence 

 extends backward more than 45 mm. beyond the pos- 

 terior epiphysis. 



Second caudal. — Distinct paired anterior haemal 

 tubercles arc not developed on the ventral surface of the 

 centrum (USNM 2379-1) ; the posterior pair of rather 

 large tubercles are separated by a wide (30 mm.) haemal 

 groove, but no remnant of the longitudinal ridge present 

 on the preceding caudal persists. The left transverse 

 process (pi. 13, fig. 2) is short and broad ; the right proc- 

 ess is broken off at the base. The left metapophysis 

 (pi. 12, fig. 2) which is complete, projects more outward 

 than upward, and extends forward beyond the level of 

 the anterior face of the centnun. The backward inclined 

 neural spine (pi. 14, fig. 1) is shorter and the neural 

 canal narrower than the preceding caudal. 



Third caudal. — The right metapophysis is broken 

 off, but otherwise this caudal (USNM 23794) is com- 

 plete. The elongate posterior haemal tubercles are sepa- 

 rated by the broad longitudinal open groove which also 

 extends forward between the smaller anterior haema- 

 pophyses. As compared with the second caudal, the 

 transverse processes (pi. 13, fig. 3) are shorter, more 

 expanded anteroposteriorly and truncated distally. On 

 their upward course from the ventral haemal groove, 

 the segmental vascular vessels (pi. 14, fig. 2) pass in 

 front of the shallow notch at the anterobasal angle of the 

 transverse process and thence follow a broad shallow 

 groove that extends obliquely backward on the lateral 

 surface of the centrum to the posterior end of the neural 

 canal. The distally truncated backward slanting neural 

 spine is reduced in height as is the narrow neural canal. 



Fourth cai-dal. — P^xcept for the missing apical por- 

 tion of the neural spine this caudal (USNM 23794) is 

 well preserved. An aproximately equal development of 

 the anterior and the posterior pair of haemal tubercles, 

 and an increase in the width of the median ventral longi- 

 tudinal haemal groove occurs first on this caudal. The 

 separation on each side of the anterior from the pos- 

 terior haemal tul)ercle by a long deep notch or gap pro- 

 vides the pathway for the segmental blood vessels on 

 their upward course on the lateral surface of the centrum 

 through the foramen that pierces the base of the short, 

 broad transverse process (pi. 13, fig. 4) medially and 

 thence obliquely to the posterior end of the neural canal. 

 The low pedicles of the neural arch (pi. 12, fig. 4) sup- 



port the thickened metapophyses which do not project 

 forward beyond the anterior face of the centrum. The 

 neural spine (pi. 14, fig. 3) has diminished in height 

 as well as in anteroposterior diameter. 



Fifth caudal. — The contour of both ends of the cen- 

 trum (USNM 23794; pi. 12 fig. 5) is almost hexagonal. 

 The ends of the short transverse processes (pi. 13, fig. 

 5) are obliquely truncated from the anteroexternal 

 angle to tlie posteroexternal angle. Both of these proc- 

 esses are pierced medially at the base for the passage 

 of the segmental blood vessels (pi. 14, fig. 4) which on 

 each side pass through the open notch between the an- 

 terior and the posterior haemal tubercles and dorsally 

 reach the neural canal through the foramen in the pedi- 

 cle of the neural arch. The median ventral longitudinal 

 haemal groove is broad and deep. The neural canal is 

 diminished to a transversely oval passage. The thick 

 metapophyses are directed obliquely upward and out- 

 ward ; the neural spine is low. 



Sixth caudal.— On this caudal (USNM 23794) the 

 profile of the posterior end of the centrum is almost 

 ovoidal in contrast to the hexagonal anterior end (pi. 

 12, fig. 6) and also is somewhat narrower. The segmental 

 blood vessels (pi. 14, fig. 5) follow the same upward 

 course from the gap between the anterior and posterior 

 haemal tubercles through the foramen at the base of the 

 abbreviated transverse process (pi. 13, fig. 6) to the 

 foramen in the pedicle of the neural arch. The median 

 ventral longitudinal haemal groove is deep but nar- 

 rower than on the preceding caudal. 



Seventh caudal.— Ventrally (USNM 23794) on 

 each side the anterior and posterior haemal tubercles 

 (pi. 14, fig. 6) are united by a thickened osseous con- 

 nection which is pierced by a foramen for passage of the 

 segmental blood vessels. Above this foramen these blood 

 vessels on their upward course pass through a vertical 

 aqueduct in the lateral portion of the centrum to reach 

 on the left side the foramen in the pedicle of the neural 

 arch. This dorsal foramen is obliterated in the right 

 pedicle. The median ventral longitudinal haemal groove 

 is deep. A thin and very low neural spine (pi. 13, fig. 7) 

 extends almost the full length of the roof of the neural 

 arcii. This roof is lacking on the caudals behind this 

 vertebra. A thick longitudinal ridge marks the position 

 of the transverse process on the preceding caudals. 



Eighth caudal.— This caudal (USNM 23794; pi. 13, 

 fig. 8) resembles the seventh caudal in having the an- 

 terior and posterior liaemal tubercles united by a thick 

 osseous connection perforated medially for the passage 

 of the segmental blood vessels from the deep ventral 

 longitudinal haemal groove. These vessels continue their 

 course upward through the vertical aqueduct in the 



