1890.] XATl'RAL SCIENCES OF PHILADELPHIA. 25 



In all the nine individuals the skin over the dorsal aspect of ulna 

 was covered with a distinct narrow tract of hair. In the adults 

 with but a single exception this line was absent. 



The crown tends to be very dark brown and unites with the side 

 of the face and the inter-ramal space by a tract— the " whisker"-which 

 extends between the ear and the eye. The color of the crown is 

 usually abruptly contrasted with that of the occiput. The space 

 between the eyes may be retained as a narrow patch of dark brown 

 which is nowhere else seen upon the crown. The occiput is almost 

 uniformly of a bright color. The back of the neck is chestnut and 

 forms occasionally only a collar. The sides of the trunk are apt to 

 be differently shaded from the front, i. e., they are either lighter or 

 darker than the front. The region of the pelvis both front and back 

 is almost uniformly woolly and darker than the adjacent fur on the 

 loin and the abdomen. 



In twenty examples the crown of the head, side of face and 

 under part of the head at the mandible tend to be differentiated from 

 the rest of the body. The whisker is marked excepting in the very 

 young. The side of the neck is less distinctly developed, yet the 

 tendency for it to be so is seen in young individuals but six inches 

 in length. The front of the neck is often sharply contrasted in color 

 with that of the side — a peculiarity not seen in any other species ex- 

 amined. The nape of the neck is apt to be of a lighter color than 

 any other portion of the body. The differentiation at the base of the 

 prebrachium is of a variable tendency. The hair of the side of the 

 body is relatively less long than in other species. The sulphur-yel- 

 low color of the back of the body is more marked in the female than 

 in the male as is the disposition for the hair of the infra-anal region 

 to be furnished with a " cowlick". The side of the tract on the 

 back tends to be margined with hairs of a different hue from the 

 one which is prevalent, as in P. vulgaris. The presence of a small 

 tract of hair on the dorsal surface of the ulna in one adult only 

 while it is detected in all the nine immature forms is a fact of in- 

 terest. 



The naked patches on the face answer nearly to the lines of 

 dark hair on the face in P. capistratus. The anterior part of the 

 dark crown in some varieties is precisely of the nature of a median 

 dorsal stripe and appears to be identical with the stripe similarly 

 situated in the species last named. 



3 



