The species to which the beautiful pair in the Menagerie belong has all the habits of its group. It is characterized by the clear fulvous brown colour of the upper surface of the body and outer side of the limbs, gradually becoming lighter on the under and inner surfaces, and deepening in its shade towards the tail, the greater part of which is nearly black. The muzzle and the hands are bluish black. The male has the whole of the forehead, the sides of the cheeks, and the under part of the lower lip covered with a white fur, which in the female is of a blackish gray and much less developed; her general colour is also of a lighter tinge. This remarkable difference would lead us to question the specific identity of the two animals, were we not assured by M. F. Cuvier that he had verified the fact by what is usually regarded as an unequivocal test. Mr. M’Leay has, however, thrown considerable doubt upon the accuracy of the inference thus attempted to be drawn, by exhibiting to the Linnean Society a female, in wh