. Bulletin - United States National Museum. Science. UTSTRECOGNIZED CALVERT CETOTHEKE 153 blood vessels follows the same course as on the fifth caudal. On the ventral surface of the centrum, the opposite haemal tubercles are separated by the broad concave longitudinal groove; the anterior pair of tubercles are smaller and narrower than the posterior pair and on each side the anterior and posterior tubercle is separated by the gap (fig. 64b) for passage of the segmental blood vessels. A very slight modification of the shape of the neural canal resulted from the further reduction in the vertical
. Bulletin - United States National Museum. Science. UTSTRECOGNIZED CALVERT CETOTHEKE 153 blood vessels follows the same course as on the fifth caudal. On the ventral surface of the centrum, the opposite haemal tubercles are separated by the broad concave longitudinal groove; the anterior pair of tubercles are smaller and narrower than the posterior pair and on each side the anterior and posterior tubercle is separated by the gap (fig. 64b) for passage of the segmental blood vessels. A very slight modification of the shape of the neural canal resulted from the further reduction in the vertical diameter (22 mm.) and the width (22 mm.); the greatest width (fig. 64a) is more dorsal than ventral. The low metapophyses do not project forward beyond the level of the anterior face of the centrum. The neural spine is small and short. In the other series (USNM 23494) the transverse processes of the sixth caudal are broader and both are pierced at the base for the passage of the segmental blood vessels; the height (29 mm.) of the neural canal is greater than the width (17 mm.) on this vertebra. The anteroposterior diam- eter (58 mm.) of the pedicle of the neural arch of this caudal is also greater than the same measurement (46 mm.) of the other vertebra (USNM 16567) as described above. The pedicles of all the caudals in this series (USNM 23494) have a greater anteroposterior diameter than those in the other series (USNM 16567). Seventh Caudal: The transverse processes of the seventh caudal (USNM 16567) are reduced to short broad flanges, pierced centrally at the base for passage of segmental blood vessels. Both ends of the centrum are hexagonal, but the epiphyses are nearly circular. On the ventral surface of the centrum the anterior pair of haemal tubercles are more proturberant than the posterior pair; these tubercles bound laterally the broad longitudinal haemal groove which is strongly concave or depressed. The anterior and posterior tubercle on each side are separated by
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