CHAP. IV] THE GENERAL ANATOMY OF THE CERCOPITHECIDAE 125 



In regard to the implantation of the hairs by groups, De Meijere 1 

 remarks that such groups are present, and that in the Cercopithe- 

 cidae they consist usually of more than three hairs. 



C. Skin Colour. The skin is subject to nearly as many 

 variations of colour as is the hairy covering of the Cercopitheci. 

 One subdivision depends in fact for its recognition on the intense 

 pigmentation of the extremities, for in this particular group they 

 are of a livid colour. In other examples local patches of skin 

 assume tints of extraordinary intensity, as for instance the green 

 coloration of the external genitalia in Cercopithecus callitrichus 

 (the " green " monkey), the dark indigo blue of the same region in 

 Stairs' Cercopithecus, or the C. cynosurus, and again the scarlet 

 hue of the ischial callosities in the latter species. The " flesh- 

 colour " of the skin in Hamlyn's Cercopithecus has been noted 

 already, and though this tint is universal in that animal, other 

 Cercopitheci exhibit localized areas of similar colour. 



This variability in the Cercopitheci places them in marked 

 contrast with the (generally sombre-coloured) Lemurs. 



With regard to definite scales or dermal scutes, the ischial 

 callosities at once occur to the imagination as a possible site for 

 such specializations. Yet, in truth, those callosities represent a 

 hypertrophy of the epidermic squamous cells en masse, rather 

 than the production of definite laminar " squamae." 



D. Hands and Feet. The notes in this section are based 

 upon the observations of Schlaginhaufen (op. tit,, v. supra, p. 69), 

 on specimens of Macacus, which is the most appropriate form for 

 consideration here. 



The exposed hairless surfaces of the palm and sole are entirely 

 covered with papillary ridges. Such an increase is distinctly 

 suggestive of a corresponding advance in the activity of such 

 functions as they subserve. Of the various " pads," all save the 

 proximal "thenar" one (v. supra, p. 69) are represented on the 

 vola or palm of the hand. 



On the plantar surface, a prominence of the heel provides for 

 a fresh extension of the corrugated area. All the " apical " pads 

 are present. The four typical " interdigital " pads are also 

 1 Morphologuches Jahrbuch, Band xxi. 1894. 



