During our next day's journey we fell in with and killed a couple of deer--a young buck and doe. They were the first of these animals we had yet seen, and that was considered strange, as we had passed through a deer country. They were of the species common to all parts of the United States' territory--the "red" or "fallow" deer (_Cervus Virginianus_). It may be here remarked that the common deer of the United States, sometimes called "red deer," is the fallow deer of English parks, that the "elk" of America is the red deer of Europe, and the "elk" of Europe is the "moose" of America. Many mistakes are made in relation to this family of animals on account of these misapplied names. In North America there are six well-defined species of deer--the moose (_Cervus alces_); the elk (_Cervus Canadensis_); the caribou (_tarandus_); the black-tail or "mule" deer (_macrotis_); the long-tail (_leucurus_); and the Virginian, or fallow deer (_Virginianus_). The deer of Louisiana (_Cervus nemoralis_) is supposed by some to be a different species from any of the above; so also is the "mazama" of Mexico (_Cervus Mexicanus_). It is more probable that these two kinds are only varieties of the _Genus Virginianus_--the difference in colour, and other respects, resulting from a difference in food, climate, and such like causes. It is probable, too, that a small species of deer exists in the Russian possessions west of the Rocky Mountains, quite distinct from any of the six mentioned above; but so little is yet known of the natural history of these wild territories, that this can only be taken as conjecture. It may be remarked, also that of the caribou (_Cervus tarandus_) there are two marked varieties, that may almost be regarded in the light of species. One, the larger, is known as the "woodland caribou," because it inhabits the more southern and wooded districts of the Hudson's Bay territory; the other, the "barren ground caribou," is the "reindeer" of the Arctic voyagers. Of the six well-ascertained species, the last-mentioned (_Cervus Virginianus_) has the largest geographical range, and is the most generally known. Indeed, when the word "deer" is mentioned, it only is meant. It is the deer of the United States. The "black-tails" and "long-tails" are two species that may be called new. Though long known to trappers and hunters, they have been but lately described by the scientific naturalist. Their _habitat_ is the "far west" in California, Oregon, the high prairies, and the valleys of the Rocky Mountains. Up to a late period naturalists have had but little to do with these countries. For this reason their _fauna_ has so long remained comparatively unknown. The geographical disposition of the other four species is curious. Each occupies a latitudinal zone. That of the caribou, or rein deer, extends farthest north. It is not found within the limits of the United States.