COLOUR PHAiiKS OF THE RUFOUS IIORSESHOK-BATS. ii69 



colour, without a trace of ajiy other tinge. In the next colour stage 

 of the fur, the auburn ]>hase, the claws are either unchanged, or 

 they begin to show a distinct deep reddening at the tips. In this 

 phase we often find one or two claws of a foot unaltered in colour, 

 while the others begin to change into deep blood-red. As a rule 

 the claws of the feet are affected a little earlier than that of the 

 pollex. Finally, in the orange phase of the fur, we find invariably 

 the claws red. The colour always starts at the tips of the claws, 

 spreading backward, though it is comparatively seldom that it 

 reaches risfht to the exnosed bases of the claws. The tinoe is a 

 beautiful blood colour, totally different from the original colour of 

 the claws ; it looks as if the claws had been dipped in blood, some- 

 times the tips onl}^, often for half their length or more. It will be 

 noticed that the colour changes of the claws progress pari passu 

 with those of the fur : — never an}' red in the claws in the non- 

 orange phases, but the more brilliant the orange of the fur, the 

 more extensive the red colour of the claws. The red colour is not 

 superficial, but goes right through the horny substance. 



The colour changes in the full grown hair described above are 

 perhaps without true parallels in the whole class of Mammalia, 

 outside the order of Chiroptera. There are, of course, numerous 

 instances of even very remarkable fading of colours. One of the 

 cases which no doubt would most readily occur to the minds of 

 British Mammalogists is the very striking and somewhat rapid 

 change of colour in the tail of the British Squirrel*. Biit I fail to 

 see any real parallel in that case. What happens in the Squirrel's 

 tail is a fading from seal-brown through gradually paler tinges of 

 brown to pale buff or nearly white ; in other words, a gradual 

 dilution, and finally complete or almost complete disappearance, of 

 all pigment in the hairs of the tail. In Rh. rovxi (and probably in 

 other bats \\'ith similar phases) the pigment does not disappear, 

 but (as we shall see in a moment) it gradually, though rapidly, 

 changes from one colour into a totally different one. There may 

 be (in fact, I believe there are) better parallels among birds. 

 Every ornithologist will know of scores of cases of alleged colour 

 change (without moult) in full-grown feathers, but I am not 

 aware of any case in which the whole of the plumage of a bird (like 

 the whole of the pelage of Rh. rou.ri and many other bats) is 

 affected by the change. 



Together with my friend Mr. Mai-tin C. Hinton (who is engaged 

 in investigations of the hair structure of certain Rodents), 1 have 

 examined the hair of Rh. rcmxi microscopically. The pigment 



• Oldfield Thomas. The seasonal changes in the Common Squirrel ; The 

 Zoologrist, November 1896, pp. 401-407. 



