1904.] PACKARD— ORIGIN OF MARKINGS OF ORGANISMS. 435 



down and chewing the cud. When they are in motion the white 

 rump may act as " follow-the-leader " or as danger signals, and 

 Pocock thinks they are not necessarily recognition marks. 



In his interesting article entitled "Antelopes and their recogni- 

 tion marks, "^ Mr. Pocock regards the face and foot markings as, 

 like the stripes, "representing spots or streaks of sunlight passing 

 through foliage or reflected from leaves." Accepting Thayer's 

 hypothesis of concealment by the counteraction of light and shade 

 and applying it to the lesser kudu, " it will be seen," he says, 

 "that the white is laid on where shadows are thrown; that the 

 white rim on the upper lip and the white chin must counteract the 

 shadows caused by the fold of the mouth and by the muzzle ; the 

 two white blotches on the neck must counteract the shadows 

 thrown by the head and by the curvature of the throat, and the 

 shadows cast by the breast and groin must be similarly obliterated 

 by the white patches on the inner side of the base of the limbs." 



That the markings or their absence are the result of adaptation 

 to the environment is clearly established by the examples given by 

 Pocock. The markings of the African elands are correlated with 

 their habits, there being " a complete gradation from the strongly 

 marked forest species through the weakly marked species frequent- 

 ing the open bush to the unmarked desert species." The kudus 

 illustrate the same principle. '^ Both the species of kudu are well 

 marked with white stripes on body and head, but the smaller 

 (S. imbefbis) is much more strikingly marked than the larger 

 {S. strepsiceros), having more stripes on the body and two patches 

 on the throat. In Somaliland, where both species occur, the larger 

 lives, according to Swayne, in the mountains, on very broken 

 ground where there is plenty of bush ; and sometimes indeed ven- 

 tures into the open plain (Inverarity). The lesser kudu, on the 

 contrary, is ' found in thick jungles .... especially where there 

 is an undergrowth of the slender pointed aloe which grows from 

 four to six feet high ' (Swayne). Evidence of a like kind is fur- 

 nished by other species of Tragelaphines The beautifully 



marked nyala (Z". angasi) and bongo (Z*. euryceros) live in dense 

 thickets; and the lovely little bush-bucks (Z. sylvatica, scriptus, 

 etc.) seldom venture out of cover except at night time to feed. 

 On the other hand the nylghaie, an aberrant member of the same 

 tribe, is without body-stripes, and lives for the most part in more or 

 1 Nature, Oct. ii, 1900, p. 584. 



