194 Systematic Paleontology 



exceedingly broad and rngous. The vertebrse in this region are relatively 

 very broad and flat. 



DIMENSIONS 



Length 96.5 mm. 



Breadth of anterior face 67.5 mm. 



Breadth of posterior face 63.0 mm. 



Depth at anterior end 43.0 mm. 



Depth at posterior end 51.0 mm. 



The dorsal (No. 4968, U. S. ISTational Museum) (pi. xv, fig. 4), was de- 

 scribed by Marsh as a posterior, but is considered by Hatcher ^ an anterior 

 dorsal, " as is evidenced by its strongly opisthocoelian characters and the 

 more extended pleurocentral cavities." Comparing it with the perfect 

 series of the small Morosaurus lentus, I should place the bone in question 

 in the mid-dorsal region as the fifth, or possibly the sixth, vertebra. 

 The curvature of the articular faces is less pronounced than in the 

 cervical described above and the lateral cavities, while deep and reaching 

 well forward, are by no means as extensive as in the cervical. Here the 

 neural canal is broad and but slightly constricted in the middle line. 

 The bone is composed of a dense cancellous tissue. The extent of the 

 suture for the neural arch is by no means so broad as in the cervicals. 

 There is in the collection a detached fragment of the neural arch which 

 is lightened by cavities as in the larger Sauropoda. 



The dimensions of the type dorsal are as follows : 



Length 95.0 mm. 



Transverse .diameter, anterior end 63.3 mm. 



Transverse diameter, posterior end 68.0 mm. 



Depth of centrum 63.5 mm. 



Maximum width of neural canal 27.0 mm. 



Minimum width of neural canal 17.8 mm. 



There are no posterior dorsals in the collection such as that described 

 by Hatcher,^ but, from the similarity between the cervical described by 

 Hatcher and that in the present instance, it is reasonable to suppose that 

 the posterior dorsals will agree approximately as well. 



^ Hatcher, Ann. Carnegie Mus., vol. ii, 1903, p. 10. 



2 Hatcher, Ann. Carnegie Mus., vol. ii, 1903, pp. 9-14, figs. 3, 4. 



