G PROF. FLOWER ON THE SKULL OF A XIPHODON. [Jail. 4, 



posterior root. Unfortunately the region in which the posterior of 

 these teeth is situated is most damaged, and its form cannot be clearly 

 made out; but, judging from the analogy of Ccenotherium, Xiphodon, 

 and allied forms, we have here the whole premolar series, the last 

 having two external, and one internal root, obliterated in the speci- 

 men, and each of the others two roots only. The canines would 

 thus be the teeth next beyond the line of fracture ; but they evidently 

 could not have been large, or deeply implanted, as in Tragulidse. 

 Of the incisors, nothing can be said from actual knowledge ; but all 

 analogies of allied forms lead to the supposition that the complete 

 number (three on each side) were present. 



It is evident that the animal to which this cranium belonged was 

 a member of that group of Artiodactyles in which the general form 

 of the modern Ruminants was shadowed out, but in which the typi- 

 cal number of teeth (eleven on each side, above and below, in con- 

 tinuous series) was still maintained, a group largely represented in 

 the North-American Miocene strata by Oreodon and its allies, and of 

 which the elegant little C<enotherium is one of the best-known 

 European forms. 



It differs, however, considerably in general form and proportions 

 from any of the former as figured by Leidy, especially in the 

 absence of a suborbital fossa, and is readily distinguished from 

 the latter by the want of the deep median notch in the hinder edge 

 of the palate, aud by the more compressed form of the premolars, 

 as estimated by the size of the roots. I am unable, however, to 

 point out any character by which to separate it from Cuvier's Xipho- 

 don, constituted in the * Ossemens fossiles ' as a subgenus of Anop- 

 lotherinm. From the type of that form, X. gracilis of the Paris 

 Upper Eocene, it differs, as far as can be inferred from descriptions 

 and figures, chiefly in superior size, being about one third larger. 



Another form to which it is closely allied is known as a British 

 fossil from the Upper Eocene of Hordwell Cliff, having been de- 

 scribed by Professor Owen under the name of Dichodon cuspi- 

 datus*. 



This animal is known by the teeth alone ; and it is singular that, as 

 far as the comparison of the size and shape of the roots or alveolar 

 walls will allow, there is no reason why the teeth of Dichodon cuspi- 

 datus should not have belonged to our present specimen. Although 

 there is not yet evidence enough to be assured of their identity, and 

 more perfect specimens of either may show that the idea is fallacious, 

 I yet think it necessary to point out the possibility. But then there 

 are grave doubts, as already expressed by Gervaisf, whether Dicho- 

 don is really separable generically from Xiphodon. The main cha- 

 racter on which the genus was founded, the peculiarity of the last 

 lower premolar tooth, was, as the original describer himself subse- 

 quently pointed out, simply the result of a milk-tooth having been 

 mistaken for a permanent one J. The British species attributed to the 



* Quarterly Journal of the Geological Society, vol. iv. 1848, p. 36. 

 t Zoologie et Paleontologie Francaise, 2 me edit. ( L859), p. 159. 

 X Quarterly Journ. Geol. Soc. vol. xiii. (1857), p. 190. 



