with a horn bent downward like that of the kuabaoba, and also because the animals of the two great varieties differ very much in appearance at different stages of their growth.  I find, however, that Dr. Smith, the best judge in these matters, is quite decided as to the propriety of the subdivision into three or four species.  For common readers, it is sufficient to remember that there are two well-defined species, that differ entirely in appearance and food.  The absence of both these rhinoceroses among the reticulated rivers in the central valley may easily be accounted for, they would be such an easy prey to the natives in their canoes at the periods of inundation; but one can not so readily account for the total absence of the giraffe and ostrich on the high open lands of the Batoka, north of the Zambesi, unless we give credence to the native report which bounds the country still farther north by another network of waters near Lake Shuia, and suppose that it also prevented their progress southward.  The Batoka have no name for the giraffe or the ostrich in their language; yet, as the former exists in considerable numbers in the angle formed by the Leeambye and Chobe, they may have come from the north along the western ridge.  The Chobe would seem to have been too narrow to act as an obstacle to the giraffe, supposing it to have come into that district from the south; but the broad river into which that stream flows seems always to have presented an impassable barrier to both the giraffe and the ostrich, though they abound on its southern border, both in the Kalahari Desert and the country of Mashona.

We passed through large tracts of Mopane country, and my men caught a great many of the birds called Korwe (’Tockus erythrorhynchus’) in their breeding-places, which were in holes in the mopane-trees.  On the 19th we passed the nest of a korwe just ready for the female to enter; the orifice was plastered on both sides, but a space was left of a heart shape, and exactly the size of the bird’s body.  The hole in the tree was in every case found to be prolonged some distance upward above the opening, and thither the korwe always fled to escape being caught.  In another nest we found that one white egg, much like that of a pigeon, was laid, and the bird dropped another when captured.  She had four besides in the ovarium.  The first time that I saw this bird was at Kolobeng, where I had gone to the forest for some timber.  Standing by a tree, a native looked behind me and exclaimed, “There is the nest of a korwe.”  I saw a slit only, about half an inch wide and three or four inches long, in a slight hollow of the tree.  Thinking the word korwe denoted some small animal, I waited with interest to see what he would extract; he broke the clay which surrounded the slit, put his arm into the hole, and brought out a ‘Tockus’, or ‘red-beaked hornbill’, which he killed.  He informed me that, when the female enters her nest, she submits to a real confinement.