------------------------------------------------------------------------------- _Huxley._ |_British_ | _Mivart._ |_Lydekker._ |_American |_Museum Case._ | | | Museum._ ------------------------------------------------------------------------------- Equus |Equus |Equus |Equus |Equus Pliohippus | | | | Protohippus |Hipparion |Hipparion |Hipparion |Hipparion | |Protohippus |Protohippus |Hypohippus Miohippus | |Anchitherium |Anchitherium |Merychippus Anchitherium|Anchitherium | |{Anchilophus |{Mesohippus Mesohippus |Protohippus |Pachynolophus|{(_form allied to_)|{ (_2 species_) |{Mesohippus | | |Epihippus Orohippus |{ (_2 species_)| |{Hyracotherium |Protorohippus Eohippus |Hyracotherium |Phenacodus |{Systemodon |Eohippus | | | |_An undiscovered | | | | ancestor_ | | | | (Hippops) ------------------------------------------------------------------------------- It will be observed, that whereas _Hipparion_ is disallowed by Professor Huxley as not being in the direct line of descent, in all the other genealogies he appears as the immediate ancestor of _Equus_. Also that in all these tables, Old World and New World forms are used indifferently to supply progenitors for the same successor. Also that there is no agreement at all as to the earlier ancestry. It would likewise appear that even the existence of _Eohippus_ himself is not beyond question, for in our Museum galleries and guide-book his name always has a note of interrogation appended. The American authorities give an anticipatory sketch of the limbs of the ancestor which still remains to be discovered. There is something even more remarkable. DEVELOPMENT OF EQUIDÆ.