In the Miocene formations we find the Feline type well developed. The wonderful _Machairodus_, which in Europe lived down to Post-Pliocene times, is found in the Upper Miocene of Dakota; and perfect crania have been discovered, showing that the chin was lengthened downwards to receive and protect the enormous canines. _Dinyctis_ was allied both to _Machairodus_ and to the weasels. Three new genera have been lately described by Professor Cope from the Miocene of Colorado,--_Bunælurus_, with characters of both cats and weasels; _Daptophilus_, allied to _Dinyctis_; and _Hoplophoneus_, more allied to _Machairodus_. The Canidæ are represented by _Amphicyon_, which occurs in deposits of the same age in Europe; and by _Canis_, four species of which genus are recorded by Professor Cope from the Miocene of Colorado, and it also occurs in the Pliocene. The _Hyænodon_ is represented by three species in the Miocene of Dakota and Colorado. It occurs {135}also in the European Miocene and Upper Eocene formations, and constitutes a distinct family Hyænodontidæ, allied, according to Dr. Leidy, to wolves, cats, hyænas and weasels. The Ursidæ are represented by only one species of an extinct genus, _Leptarchus_, from the Pliocene of Nebraska. From the Pliocene of Colorado, Prof. Cope has recently described _Tomarctos_, as a "short-faced type of dog;" well as species of _Canis_ and _Martes_. _Ungulata._--The animals belonging to this order being usually of large size and accustomed to feed and travel in herds, are liable to wholesale destruction by floods, bogs, precipices, drought or hunger. It is for these reasons, probably, that their remains are almost always more numerous than those of other orders of mammalia. In America they are especially abundant; and the number of new and intermediate types about whose position there is much difference of opinion among Palæontologists, renders it very difficult to give a connected summary of them with any approach to systematic accuracy.