1892.] SPECIES OF THE HYRACOIDEA. 57 



A. Dorsal spot wholly black P. capensis, shoana. 



B. Dorsal spot whitish, yellowish, or orange, 



a. Spot comparatively small, roughly oval in shape. 



a}. Hairs of spot, or at least the central ones, wholly yellow. 



P. syriaca, pallida, 

 h^. Hairs of spot with dark bases and generally black tips. 



P. ruficeps, ahyssinica. 



b. Spot elongate, linear. 



e^. Hairs pale coloured to their bases. 



a^. Spot orange or cinnamon P.valida. 



h-. Spot pale yellow or whitish. 



P. hrucei, bocagei, latastei, welwitschii, and arborea. 

 d} . Hairs black at base, white terminally P. dorsalis. 



The central part of the dorsal gland is very commonly quite 

 naked, notably in P. dorsalis, where the naked part is two or three 

 inches long, and about half an inch broad. Owing, however, to the 

 way in which the hairs round the naked part converge towards each 

 other, this fact is very seldom observable without separating the 

 hairs, but occasionally in old specimens the naked skin is clearly 

 visible from above. The distinctions given above between the 

 different sorts of spots are by no means to be taken au pied de la 

 lettre for every specimen examined, many of the groups passing 

 quite imperceptibly into each other, while in some species the spot 

 itself varies so much as to be not easily definable. 



As to the geographical distribution of the different species the 

 accompanying sketch-map (see p. 58) will show more clearly than any 

 amount of description where the different forms are found, and will be 

 a guide to anyone wishing to know what species may be expected to 

 occur in any given locality, It may, however, be just noted that while 

 many places have only one species known from them, most have two, 

 and that these are almost invariably one of the hypsodont (Procavia) 

 and one of the brachyodont {Dendrohyrax and Heterohyrax) groups. 

 Thus in N. Abyssinia we have P. brucei and ahyssinica^ in Shoa 

 P. brucei and sJioana, in Angola P. bocagei and welwitschii, and in 

 S. Africa P. arborea and capensis. 



The two tables exhibited (see pp. 59, 60) show respectively (1) the 

 basal lengths ^ of considerable series of specimens of each species taken 

 at as many age-stages as possible, and (2) (a) the breadth of m^, 

 (5) the height of m^, measured as already described, and (c) the hori- 

 zontal length of p^. It is to be hoped that, without a more formal 

 synopsis, which at present I hardly feel capable of drawing up, these 

 measurements, combined with the rough synopsis of the dorsal 

 spots just given, will enable anyone to determine specimens without 

 much difficulty. 



^ Basion to gnathion. 



