528 dr. g. e. dobson on the [June 20, 



The fore foot 1ms 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. H. 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 ca- 

 pensis by Messrs. Murie and Mivart and by Prof. J. F. Brandt 

 have afforded me great assistance in my examination. 



Hyrax dorsalis may be taken as a representative of that section 

 of the genus in which the climbing-powers are, apparently, most de- 

 veloped, 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 solu- 

 tion of cyanide of potassium almost restored them to the original 

 soft condition, which we know (from Bruce and Schweinfurth's de- 

 scriptions 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 pha- 

 langes ; 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. 



