FROM INDIA AND THE ISLE 0E WIGHT. 



159 



the dorsal vertebrae are amphicoelous, Professor Marsh's * figure 

 and description show that the hinder caudals have neural arches 

 of the precise type of those of Titanosaurus, while the form of 

 the middle part of their centra is apparently very similar to 

 that of the specimens under consideration. In Oamarasaurus, 

 again, the centra are laterally compressed as in Titanosaurus 

 indieus, although the facets for the chevrons are less strongly 

 marked. Oamarasaurus and Amphicoelias, it may be observed, are 

 of Cretaceous, while Brontosaurus is of Jurassic age. The suborder 

 Sauropoda is taken to include Oetiosaurus, which, although none 

 of the vertebral centra are hollowed, is evidently allied to Orni- 

 thopsis ; while it is probable, judging from the structure of the 

 caudal vertebrae, that Macrurosaurus should also be placed in the 

 same division. There appears therefore to be at least a consider- 

 able degree of probability that the Wealden vertebrae may belong 

 to Ornithopsis ; and if they do not it is pretty certain that they do 

 not belong to any other previously known English genus. 



With regard to the second question — i. e. whether these vertebrae, 

 which may be provisionally referred to Ornithopsis, are generically 

 identical with one or both of the two forms described under the 

 name of Titanosaurus — there is far less possibility of arriving at 

 present at any very satisfactory conclusion. It will, however, 

 be safe to say that if the characters which distinguish the vertebrae 

 of Titanosaurus indicus from those of T. Blanfordi eventually 

 prove to be of not more then specific value, then the English 

 vertebrae might well be also generically identical, in which case 

 Titanosaurus should be merged in Ornithopsis. If, however, on the 

 other hand, the vertebrae described under the name of T. Blanfordi 

 should turn out (as it is highly likely that they will) to be 

 generically distinct from T. indicus, then there would also be very 

 considerable probability that the "Wealden specimens are likewise 

 generically distinct from both the Indian forms, although their 

 relationship appears nearest to the form called T. Blanfordi. 



Under these difficult circumstances the only prudent course is to 

 consider that we have evidence in India and Europe of three appa- 

 rently closely allied Dinosaurs clearly marked off from all other 

 described forms by their strongly procoelous later caudal vertebrae, 

 and for the present to retain the generic name Titanosaurus for the 

 type Indian species, to refer the Wealden form provisionally to 

 Ornithopsis, and to leave it open whether the form to which the 

 name Titanosaurus Blanfordi has been applied is generically iden- 

 tical with one or other or even both of these forms, or whether it 

 should form the type of a third genus f . 



In conclusion, it may be observed that the occurrence in the 



* Amer. Journ. vol. xxvi. pi. i. (1883), and vol. xxi. p. 420 (1881). 



t In my description of Titanosaurus I mentioned a larger vertebral centrum 

 which. I regarded as precaudal and procoelous. Since, however, similar vertebras, 

 which are opisthoccelous, occur at Brook, the two types may respectively 

 belong to the early caudal region of the Indian and European Dinosaurs, 

 as the Crocodilia and Macrurosaurus show that the form of the articular surfaces 

 of the centra may vary in different parts of the caudal region. 



