_Insectivora._--This order is represented by comparatively few forms in the tertiary beds, and these are all very different from existing types. In the Upper Miocene of Dakota are found remains indicating two extinct genera, _Lepictis_ and _Ictops_. In the Miocene of Colorado, Professor Cope has recently discovered four new genera, _Isacis_; allied to the preceding, but as large as a {134}_Mephitis_ or skunk; _Herpetotherium_, near the moles; _Embasis_, more allied to the shrews; and _Dommina_, of uncertain affinities. Two others have been found in the Eocene of Wyoming; _Amomys_, having some resemblance to hedgehogs and to the Eastern _Tupaia_; and _Washakius_, of doubtful affinities. Far back in the Triassic coal of North Carolina has been found the jaw of a small mammal (_Dromotherium_), the teeth of which somewhat resemble those of the Australian _Myrmecobius_, and may belong either to the Insectivora or Marsupials; if indeed, at that early period these orders were differentiated. _Carnivora._--The most ancient forms of this order are some remains found in the Middle Eocene of Wyoming, and others recently described by Professor Cope (1875) from the Eocene of New Mexico, of perhaps earlier date. The former consist of three genera, _Patriofelis_, _Uintacyon_, and _Sinopa_,--animals of large size but which cannot be classed in any existing family; and two others, _Mesonyx_ and _Synoplotherium_, believed by Mr. Cope to be allied to _Hyænodon_. The latter consist of four genera,-- _Oxyæna_, consisting of several species, some as large as a jaguar, was allied to _Hyænodon_ and _Pterodon_; _Pachyæna_, allied to the last; _Prototomus_, allied to _Amphicyon_ and the Viverridæ; and _Limnocyon_, a civet-like carnivore with resemblances to the Canidæ.