Considerazioni sistematico-genetiche sulle famiglieEquidaeeUrsidae

Abstract

Summary The prove of the absolute sterility of the males and relative, for some cases of fertility, of the females of the hybrid ones obteined among the various systematical species of the family Equidae, justifies the recent proposal of Bourdelle about the fractionising of the complex genus Equus into five distinct genera: Equus (Horse), Hemionus or asiatic Wild Asses), Asinus (african Wild Asses), Hippotigris (Zebras of the type Quagga and mountain's Zebras), Dolichohippus (Grevy's Zebra). On the contrary, the complete fertility of the hybrid ones botle feminine and masculine (this last more sensible to the negative influence which comes from the hybridation) betwen two systematical species of the family Ursidae, one belonging to the genus Thalarctos (T. maritimus, polar Bear) and the other to the genus Ursus (U. arctos middendorffi, brown Bear of Alaska or Kodiak), makes convenient — in the author's opinion — the simplification on the systematical classification of the family by the union of the numero...