COLOURS AND PATTERNS OF MAMMALS 91 



as the young Selous' sitatunga. The splendid bongo and angas 

 antelopes retain the spots and hoops of the young in both sexes, 

 although in the latter the adult male becomes nearly black. The 

 young harnessed antelope has spots on the hindquarters, stripes 

 along the side, and barrel hoops across the back, and a general 

 reddish hue very hke the young sitatunga ; whilst these fade but still 

 remain visible in the darker adults. The male nilgai or " blue bull " 

 of India is bluish-black, whilst the female and the young are tawny 

 and there is no trace of spots and stripes in any of them. 



In antelopes generally there is to be noticed the same general 

 tendency that occurs amongst the carnivores. When the young 

 differ in pelage from the adults, they resemble the females more 

 closely than the males ; they show far less trace of special ruptive 

 and secant patterns, of those patterns which follow the primitive 

 contours of the body least, and show frequent traces of spots and 

 stripes, and similar simple growth patterns. 



The prongbuck or American antelope, which lives in upland 

 prairies and on rocky slopes where the snow lies in patches imtil 

 late in spring, and descends again in early autumn, is one of the 

 most striking examples of ruptive pattern. The back is rich tan 

 with black on the head, and great disks of white on the rump, whilst 

 the face and sides have patches and areas of white sharply marked 

 off from the darker regions. The females have similar but less 

 brightly marked patterns, whilst the young are almost uniformly 

 clad in pale greyish- brown with only the faintest trace of the adult 

 coloration. Here is another instance of one of the highly specialised 

 patterns which cannot be easily associated with the natural structure 

 of the body, appearing only with adult life. 



The well-known pattern of the Giraffes (see Plate II, p. 11) suggests 

 in a vivid way the origin of colour pattern from the tessellated or 

 particulate character of the skin. It consists of a series of spots or 

 blotches which grow darker with age, placed on a pale background, 

 and in some species leaving only a narrow reticulation of the pale 

 ground between the spots. The young, as soon as they are born, 

 show the spots clearly marked. Many hunters have borne witness 

 to the fashion in which this apparently vivid pattern makes the 

 animal almost invisible as it stands under the trees on which it 

 feeds, and it appears as if the pattern were a simple growth form 

 that had been retained because it was either positively useful or at 

 least harmless. 



Deer show a most interesting set of differences in the relations 



