The ruminating animals exhibit a fair amount of intelligence, never, however, attaining that power of perception and memory exhibited by the Carnivora and other higher forms. The figure of the surface of the brain of the Sheep indicates that the convolutions of the brain are far from inconsiderable in number, and its allies of the same size agree with it in this respect, whilst larger species have more, and smaller less elaborate brain-markings, as is nearly always found to be the case in every group. The accompanying table gives an outline sketch of the classification of the ruminating animals which has been adopted by zoologists:-- _Sub-order._ _Section._ _Division._ _Group._ { Ox-tribe { (_Bovidæ_). { HORNED RUMINANTS. { { { Deer-tribe { TRUE RUMINANTS. { { (_Cervidæ_). { { CHEVROTAINS OR RUMINANTIA. { { DEERLETS { CAMEL TRIBE. { (_Tragulidæ_). { (_Tylopoda_). The large sub-order of the Ruminantia is seen to be primarily divided into two sections, namely, the typical Ruminants and the aberrant Ruminants (the _Tylopoda_). The typical Ruminants, in which the stomach is formed upon the plan of that described above in the Oxen, fall into two divisions, the smaller of which--that of the Chevrotains or Deerlets--possesses no psalterium, or third stomach, except in a rudimentary condition. The Horned Ruminants, including the Deer, Muntjacs, Elk, Oxen, and Antelopes, compose by far the largest number of the whole sub-order, and will be first described. HORNED RUMINANTS. The Horned Ruminants--with which, anomalous as it may at first seem, have to be included one or two hornless species, on account of their so closely resembling them in other respects--have their _cranial appendages developed after one or other of two principles_. In one group, which, from the fact that the Oxen are included with them, are named the _Bovidæ_, the horns are hollow, straight, or variously-twisted cones, supported upon bony prolongations from the forehead, resembling them in shape upon a smaller scale. These horns are permanent, except in the American Antelope, increasing in size each year, at the same time that they often exhibit transverse markings, which indicate the annual increase. In the other group--the _Cervidæ_, or Deer Tribe--the horns or antlers are deciduous, being cast off each year, to be shortly replaced by others, which share the fate of their predecessors. These antlers are entirely made of bone, and when fully grown are not covered with any less dense investment. To commence, then, with the _Bovidæ_, or Oxen, and their allies. THE BOVIDÆ, OR HOLLOW-HORNED RUMINANTS.