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Show 528 DR. G. E. DOBSON O N T H E [June 20, The fore foot has four toes, three disposed in the same proportion as on the hind foot; the fourth, the largest of the whole, is placed lower down on the side of the foot, so that the top of it arrives no further than the bottom of the toe next to it. The sole of the foot is divided in the centre by a deep cleft like the other; and this cleft reaches down to the heel, which it nearly divides. The whole of the fore foot is very thick, fleshy and soft, and of a deep black colour, altogether void of hair, though the back or upper part of it is thickly covered, like the rest of its body, down to where the toes divide." " The centre cleft " of Dr. Schweinfurth appears to be the groove represented in Plate LV. fig. 9, and Fig. A, which passes backwards from a slight concavity in the centre of the sole of the foot and divides the heel. I am unable to feel equally satisfied with that distinguished traveller that the simple acts of opening and closing that cleft or any cleft in the foot are sufficient to enable the animal " to throw off part of its weight and to gain a firm hold upon the smooth surface of the stone." In the ordinary condition of the foot, the central concavity is evidently not of sufficient depth or extent to cause the strong adhesion of the sole to the rock as described. I believe that the source of this remarkable adhesive power may be traced in the general structure of the extremities. Through the kindness of Prof. W . II. Flower, I have been enabled to examine the structure of the extremities in a specimen of Hyrax dorsalis preserved in alcohol in the Museum of the Royal College of Surgeons ; and the valuable treatises on the myology of Hyrax capensis by Messrs. Murie and Mivart and by Prof. J. F. Brandt have afforded me great assistance in m y examination. Hyrax dorsalis may be taken as a representative of that section of the genus in which the climbing-powers are, apparently, most developed, the animals of this species inhabiting holes in trees, on the vertical stems of which they run up and down with the greatest facility. The habits of the species of this section suggested the sub-generic name Dendrohyrax. In the specimen of Hyrax dorsalis examined by me the soles of the feet had become quite hard and rigid from the action of the alcohol in which it was preserved ; but prolonged immersion in solution of cyanide of potassium almost restored them to the original soft condition, which we know (from Bruce and Schweinfurth's descriptions made from examination of the living animal in its native country) is the normal state of the sole of the foot during life. In all climbing four-footed animals the anterior extremities perform by far the most important part in maintaining their hold; and the species of Hyrax form no exception to this rule. The fore foot has five toes (one, the pollex, being rudimentary and concealed beneath the skin) ; the hind foot three only (Plate LV. fig. 9). The toes are united as far as the bases of the terminal phalanges ; the outer toe of the fore foot is united along its whole length. The nails are flat and short; and beyond them the soft extremities of the toes project, except in the case of the inner toe of the hind foot, |