232 Bulletin Atnerican Museum of Natural History. [Vol. X, 



D 4. Behind this would appear 

 the transversely expanded mid- 

 dorsal spines of the Brontosaurus^ 

 (Fig. 12) type, and of our speci- 

 men, No. 222 (Fig. 2). Behind 

 this again would appear the pos- 

 terior dorsal of the Ahiphicoelias 

 type (Fig. 13) or the still more 

 posterior dorsal of our specimen, 

 No. 222 (Fig. 3). 



The difference between these 

 three types of vertebras (Figs. 9, 

 12 and 3) is so profound that it 

 seems hardly possible that they 

 could be compressed within the 

 limits of 14 dorso-lumbars — the 

 number which Marsh has figured 



Fig. II. Catnarasaurus supremus. 

 Anterior dorsal. Supposed to be the 

 first possessing a median spine. After 

 Cope. Approximately j'g natural size. 



Fig. 12. 



Fig. 13. 



Fig. 12. Broniosaurus ejrcelsus. Dorsal vertebra. After Marsh, 1897, Plate xxi. Approxi- 

 mately j'g natural size. 



Fig. 13. Posterior dorsal of Amphiccelias alius, type. After Cope. Approximately i'b 

 natural size. 



' This is mistakenly determined by Marsh ('Dinosaurs of North America,' p. 169) as a 

 "posterior dorsal." 



