398 ON THE FOSSIL BONES OF PACHYDERMATOUS QUADRUPEDS. 



fbtsil bones, has been the greater or less number of those of the hip- 

 popotamus which have been discovered. 



Thus, I have seen two well characterised jaw teeth in the Museum 

 of the University of Pisa, which were found in the lower Valley of the 

 Aino. At Bologna, besides the teeth mentioned by Aldrovandus, I 

 observed a fine lower head of a femur. In the Museum of the Roman 

 College at Rume there are some tusks found in the neighbourhood of 

 that city. 



As for France, besides the pieces found in the neighbourhood of Mont- 

 peliier, which I have already mentioned, some others have been dis- 

 covered quite close to Paris. I have deposited, in the King's Museum, 

 a very fine tusk extracted from the sand in the plain of Grenelle. 



The Abbe de Tersan was likewise possessed of a jaw tooth found in 

 the same quarter, and which appeared to have lain in a ferruginous 

 white gravel. 



Again, in England, Mr. Trimmer has found some at Brentford, in 

 Middlesex. They consist of a tusk, two incisors of the lower jaw., an 

 entire jaw tooth, and the fragment of another — all represented in the 

 Philosophical Transactions of 1813, plates 9 and 10. They were in a 

 large depot, with the bones of the elephant, the rhinoceros, and the 

 stag, to which I have alluded elsewhere. 



These facts must at once remove all doubt of the fossil remains 

 of the hippopotamus being found in several places, in conjunction with 

 the bones of the elephant, the rhinoceros, and the mastodon ; but it 

 is rather singular that the only country in which they have been found 

 in quantities proportioned to those of the other species, should be the 

 upper Valley of the Arno. 



No other country has yielded more than inconsiderable fragments, 

 and those in small quantities. 



Hence it is to the specimens found in the Valley of the Arno that I 

 shall chiefly have recourse in founding those comparisons,by whichl shall 

 prove that the fossil and the living hippopotamus differ as widely as the 

 fossil elephant and the fossil rhinoceros, from the species of our times. 



II. Osteological Comparison of the Gi-eat Fossil Hippopotamus with 

 the living Species. 



The distinguishing characters of the great fossil hippopotamus are 

 not quite so easily perceptible as those of the elephant and rhinoceros 

 of the same time ; and, as long as the relics of the former were limited 

 in number, and I had no complete skeleton of the living hippopotamus 

 to compare them with, I almost despaired of being able to assign any 

 positive difference ; but the uncertainty in which I found myself, at 

 the period of the publication of nry first edition, has been happily dis- 

 sipated ; almost all the bones, taken one by one, in the two species, 

 show marked differences, and the geological rule relative to the strange 

 genera is found applicable to this as to all the other species. 



1. The Head. 



The fossil head (plate 35, figs. 1 and 2), -viewed from above, has its 

 occipital crest narrower, the zygomatic arches less widely apart to- 

 wards the rear, the portions of the skull bounded at the sides by three 



