402 THE NA.TUEAL HISTOEY REVIEW. 



Pembrokeshire, and Durdham Down near Clifton. I have identified 

 the remains from Kirkdale, and the caves of Pembrokeshire in the 

 Bucklandian Collection at Oxford. Those from Durdham Down 

 associated with Ursus spelceus, Hippopotamus major, and Elephas 

 antiquus, are preserved in the Bristol Museum. Both upper and 

 lower jaws, associated with Hippopotamus major, have been obtained 

 from the river deposits at Lexden, near Colchester. A comparison 

 of the leptorhine with the tichorhine bones proves the former to have 

 been a smaller and more slender animal. 



Closely allied to the B. leptorhinus of Professor Owen in many 

 points, but differing materially in its larger size, and the enormous 

 development of its nasals, is the third species named by M. de 

 Christol from its latter characteristic, R. megarhinus.^ In his type 

 specimen, from Montpellier, the bony septum is absent. He enu- 

 merates five points of diff*erence between the upper molars of the 

 megarhine and the tichorhine species. f " 1. Ces molaires (megar- 

 hiue) n'ont habituelment que deux fossettes sur la couronne. 2. 

 Le crochet de leur coUine posterieure ne se joint jamais k I'anterieure. 

 3. Ce crochet est bifurque ou trifurque dans les molaires de rem- 

 placement, et simple dans les arriere molaires. 4. Tin crete verti- 

 cale part Tangle de la couronne et se dirige vers Tissue du vallon. 

 5. Un large bourrelet est applique centre le bord interne des molaires 

 de remplacement." These characteristics apply with but slight 

 modifications to the leptorhine teeth also ; but as the latter was not 

 properly defined as a species until the year 1846, M. de Christol, 

 who wrote in 1835, cannot be blamed for not being cognisant of the 

 existence of two species very closely allied in their dentition. The 

 vast accumulation of materials for satisfactorily defining the species 

 of fossil Ehinoceros in our great National Collection, and in many 

 private museums, give the naturalist of the present day opportuni- 

 ties, such as Cuvier, Pallas, De Blainville, and De Christol never had. 

 Out of it I have chosen the milk and permanent dentition of JR. 

 megarhinus for the subject of this essay, as being the most imper- 

 fectly known of the three Pleistocene species. In mapping out the 

 various parts of the teeth I have followed the system of Professor 



* Recherches sur les caracteres des grandes especes de Rhinoceros fossiles, Ann. 

 Sc. Nat. 2nd series, Zool. Tom 4, 1835, p. 42-112. 

 t Op. cit. p. 95. 



