746 THE POPULAR SCIENCE MONTHLY. 



shape, and there is not space for the strong muscular system arching 

 over the neck like a cowl, whicli is so characteristic of the gorilla. 

 The head of the chimpanzee displays, both in aged and young speci- 

 mens, the concave neck which is common among apes, that is to say, 

 a depression between the head and the throat. In an aged male the 

 crown of the head presents a rounded, arched contour, since, as we 

 have already said, the prominent bony processes are wanting. Al- 

 though the supraorbital arches are not so excessively prominent as in 

 a gorilla of the same age, they are strongly developed, covered with 

 wrinkled skin, and in this case also there is a species of e^^ebrow, stiff 

 and bristly, with shorter hairs between. The large, wrinkled lids are 

 furnished with thick eyelashes. The inner angle of the eye somewhat 

 resembles that of the gorilla. 



A general physiognomical distinction between the gorilla and the 

 chimpanzee consists in the fact that the bridge of the nose is shorter 

 in the latter than in the former. In the chimpanzee this part of the 

 organ is depressed, yet the depression is of a conical and convex form, 

 and is covered with a net-work of wrinkles of varying depth. In the 

 chimpanzee the interval between the inner angle of the eye and the 

 upper lateral contour of the cartilaginous end of the nose is shorter 

 than in the gorilla. There is also some difference in the form of the 

 nose : it is on the whole flatter, the tip is less apparent, the nostrils 

 are not so widely opened nor so thickly padded. (Fig. 3.) In the 

 chimpanzee, as well as in the gorilla, a central and vertical furrow 

 directly divides the triangular nostrils, and these are likewise divided 

 from the rest of the face by the broad pear-shaped furrow which sur- 

 rounds them. The upper lip is generally high, sometimes as high as 

 thirty millimetres ; but in some individuals it is much lower. As in 

 the gorilla, the chin forms a triangle of equal sides, with its apex 

 reversed. 



The external ear of the chimpanzee has on the whole less resem- 

 blance to the human ear, and its contour is larger than that of the 

 gorilla. But this organ varies so much in individuals that it is difficult 

 to lay down any rule for its average size. It ranges from fifty-nine to 

 seventy-seven millimetres in length, and from forty-two to eighty 

 millimetres in width. Many individuals have a distinct lobule to the 

 ear, others not. (Fig. 5.) In this example the helix and anti-helix are 

 developed, in others they are wanting. The tragus and anti-tragus 

 are more or less apparent in different individuals, as well as the other 

 modifications of the external cartilage of the ear. 



An aged male chimpanzee has broad, rather rounded shoulders, a 

 powerful chest, long, muscular arms, I'caching to the knees, and a long 

 hand, which seems to be very slender in comparison with that of the 

 gorilla. The thumbs vary in length, for the most part reaching as far 

 as the metacarpal phalanges, but not in all cases. The middle finger 

 is longer than the other three ; the first and third fingers are shorter 



