Related to _Palaeosyops_ is another primitive Titanothere, the genus _Telmatotherium_. This is also Eocene, from the Uinta Basin, the uppermost of Eocene strata. The skull of these creatures was rather elongated, and not unlike that of a Titanothere in general aspect. The dentition was complete and the canines not very large. The horns, which acquire so prodigious a development in the later Titanotheres, are just recognisable in at any rate many species of this genus _Telmatotherium_, the name being thus by no means an apt one. Better was that proposed by Dr. Wortman, of _Manteoceras_ or "prophet horned." The horns are small elevations upon the frontals just at the junction of these with the nasals, and, indeed, lying partly upon the latter bones. In _T. cornutum_ the horns are chiefly borne upon the very long nasals, whose size contrasts with the same bones in the more highly-developed _Titanotherium_. It appears to be quite possible that _Titanotherium_ was evolved from the genus _Telmatotherium_.[177] SUB-ORDER 9. LITOPTERNA. Whether the MACRAUCHENIIDAE should be considered as a separate group of Ungulata is a matter of dispute. Cope placed them in a special order of Ungulates which he called Litopterna. Zittel, on the other hand, regards them as definitely Perissodactyles. One curious point of resemblance to existing Horses is shown--that is the presence of a pit in the incisor teeth. This matter seems to be so important as to need a placing of these forms in the neighbourhood of the Perissodactyles, even of the Equidae; it is so peculiar a character, and apparently so little related to any obvious similarity in way of life, that it seems to mark a special affinity. Not so the fact that in _Macrauchenia_ at any rate the orbit was entirely surrounded by bone as in the Horse. We find that condition so frequently acquired in many groups,--a development from an earlier condition where the cavity for the lodgment of the eye is in continuity with the temporal {268} fossa, that it cannot be regarded as anything more than a mark of specialisation. It is, in fact, the case that the Macraucheniidae are in many points specialised, while retaining many primitive features of structure.