656 Bulletin American Museum of Natural History [Vol. LXVI 



External Characters. — The external appearance of a living 

 adult female, taken at Avakubi, November 10, 1909, was described by 

 Mr. Lang in the following words: " Snout and skin around eyes pinkish 

 brown, lips pinkish, iris dark brown. The skin that may be seen under- 

 neath the hair behind the eyes and around the ears is grayish. The 

 visible skin on the fore and hind limbs dirty gray; throat, abdomen, and 

 skin around anus, also the underside of legs, grayish white." The 

 collector recorded the eye color of another female as medium brown and 

 noted that the pupil was circular. The nose of a third female is described 

 as " grayish above, somewhat brownish." 



A male taken at Stanleyville, August 9, 1909, was characterized as 

 follows: " Snout pinkish gray, underlip whitish, iris dark brown, eyes 

 much protruding from the thick, swollen looking eyelids. Ears can be 

 closed though they are often open, a simple slit outside, but supported 

 by a cartilage." 



Age Changes in External Characters. — The splendid series of 

 tricuspis from a small area in the upper Congo basin shows extreme limits 

 of variation in the contour, size, and count of the scales and the color, 

 length and density of hair that embraces practically the entire range of 

 variation that I have seen in specimens from Liberia, the Ivory Coast, 

 Cameroons, Fernando Po, Gabun, the lower Congo, Kasai district, and 

 central Angola. 



The scales do not increase in number but grow in length and breadth. 

 Throughout life they are deeply striate, but in old age the scales of the 

 head and the tips of all scales, become worn smooth. At birth, and from 

 that time until the individual attains a length of about 325 mm., the 

 margins of the scales are even, but with ensuing wear, which by action 

 between the scales is concentrated on the section bordering the median 

 keel, the scales become sharply dentate, or, usually later, tridentate. 

 This configuration of the scale margins is characteristic of youth, and 

 usually disappears, particularly dorsally, by the time the individual 

 reaches a length of 750 mm. During the period from youth to old age 

 the scales grow in length more rapidly than in width, a scale from the 

 mid-dorsal region transforming from a structure as wide as long to one 

 in which the length is four times the width. Old animals with cuspless, 

 worn, elongate scales present a drastically different appearance from the 

 animals aptly described by their specific name. (Compare figures 1 and 

 2, Plate XXXVI.) 



Hair changes during life are striking but subject to well-marked 

 individual variation. At birth and for some time afterward the only 



