1907.] MONKEYS FROM THE AMAZONIAN REGION. 95 



Examining in the same manner the two skins of half-grown 

 individuals ( $ , d), we see immediately, that while the lowei- 

 half is dark as above, the outei- half shows alternately a light 

 zone, then a dark one, and iinally the terminal lighter one, giving 

 as a total result the impression of only one complete pair of 

 light and dark zones. The female skin presents nevertheless i\ 

 peculiarity in the circumstance that near the i-oots of the hairs 

 there is an unmistakable trace of a basal light zone — a peculiarity 

 of this one individual among all the five known. 



Proceeding now to the examination of the same details in 

 the quite young stuffed specimen of the mounted family in the 

 Para Museum, the general impression is of only one well-marked 

 pair of dai-k and light zones, from within outwai'ds, while on closei' 

 inspection the second outer pair noticed in the half-grown speci- 

 mens is unquestionably recognisable. 



Recapitulating these facts, the general conclusion is that the 

 number of light and dark zones tends to increase with age. We 

 have here one more useful hint, that in the discrimination of species 

 prudence is requii'ed in judging the value to be attributed to 

 such variations in colour, which in the present case can be fairly 

 proved to be due to differences of age and sex. 



Head. All parts of the full front view of the face and direct 

 lateral view are sooty-black in the adult female, the quite young- 

 individual ( (5' ) and the two skins ((:?$), while the old male 

 shows the face somewhat mixed up with greyish-brown hairs. 

 The circumbuccal zone, however, is again an exception from 

 this general colour, being saliently pure white. This zone is 

 relatively broader than in any of the preceding species, including 

 the entire nostrils in the old male, while in the other four sj)eci- 

 mens the border-line of the white colour curves below the nostrils, 

 arising again on the ridge of the nose at about one-third of its length. 

 The same white colour characterises the phenomenal moustache, 

 which already in infant specimens is of a greater length than in 

 any other of the moustached species known to me. The old 

 male (text-fig. 23), however, beats the world's record, the longest 

 hairs attaining a length of no less than 57 to 60 mm. ! 



My collectors inform me that the moustache is worn in life not 

 straight, but with the modern upward twist. The two oldest 

 specimens show the strange strong development of the white hairs 

 of the circumbuccal zone extending even over the whole area of 

 the lower jaw, not including the chin and inferior side of the jaw. 

 As a result, the old males appear bearded as well as moustached. 



In the three younger individuals the crown of the head is 

 brownish-black, with a tendency towards forming the already 

 familiar favourite lighter-coloured 23atch of a jDale brownish shade. 

 In the adult female the patch is diamond-shaped, almost dirt}' 

 greyish-white, and therefore very conspicuous. In the old male 

 a pronounced greyish cast spreads all over the top of the head, 

 without forming any distinct patch. 



Arms. Outer side of upper arm the same colour as the back, 



