Vol. 51.] SATJROPODOUS DINOSAT7R FROM MADAGASCAR. 



335 



There are, however, in the British Museum certain dorsal vertebrae 

 which, although of much smaller dimensions, agree precisely with 

 those of the form under consideration in structure. The first of 

 these are from the Kimeridge Clay, and were described by Owen 

 under the name of Bothriospondylus suffossus, of which genus they 

 constitute the type. They indicate a very immature dinosaur, and 

 from their immaturity I have thought that they might belong to 

 the young of one of the other genera. 1 These specimens have the 

 lateral pits precisely similar to those in the dorsal vertebra of the 

 Malagasy form, while a comparison with the latter shows that 

 the dividing septum was of the narrow type. The whole bone, 

 moreover, appears to be devoid of cancellation. Formerly I thought 

 it possible that these features might be those of the immature state 

 of forms like Hoplosaurus, but the specimens before us clearly 

 demonstrate that this is not the case. Another dorsal vertebra of 

 similar type, from the Forest Marble of Wiltshire, was likewise 

 referred by Owen to Bothriospondylus, under the name of B.robustus. 

 This specimen, represented in fig. 6, likewise agrees in all respects 



Fig. 6. — Lateral and superior aspects of centrum of dorsal vertebra 

 of Bothriospondylus robustus. {About 5 nat. size.) 



with the dorsal vertebra from Madagascar ; and it is quite clear 

 that, with the materials at present available, it is impossible to 

 separate generically the two forms. I accordingly propose to refer 

 the Malagasy dinosaur to the genus Bothriospondylus (which is now 

 for the first time susceptible of definition) under the name of 

 B. madagascariensis, taking the dorsal vertebra represented in fig. 3 

 (p. 331) as the type : the species being sufficiently characterized by 

 its large size. 



"We have thus evidence that Bothriospondylus indicates a type of 

 sauropodous dinosaur quite distinct from, and apparently much less 

 specialized than, the Atlantosauridae (in which Hoplosaurus and 



1 See Cat. Foss. Eept. Brit. Mus. pt. iv. (1890) p. 242. 

 Q. J. G. S. No. 203. 2 u 



