MOULT AND REGENEEATION OF PELAGE IN MICE 75 



flight is not impaired, there are cases in which the process is not 

 so plainly adaptive. 



The Duck family (Anatidae), among others, according to Coues, 

 drop their wing quills so nearly simultaneously as to be for some 

 time deprived of the power of flight. 



The details of the process of moult are not so well known in 

 the case of mammals. However, it appears that in general the 

 process is more irregular than in birds. According to Allen ('94) : 

 "As a rule, particularly among the Rodentia, the change be- 

 comes first apparent on the feet and about the nose extending 

 gradually up the limbs and over the head and from the base of 

 the tail anteriorly, and from the sides of the body toward the 

 median line." This appears to be the usual method especially 

 in the spring moult, but the process is said to be ''subject to 

 much irregularity, even among individuals of the same species, 

 and it seems to vary somewhat in different groups" (p. 107). 



In describing the condition in rabbits Nelson ('09) says that 

 ''the moults usually begin about the head and feet and proceed 

 more or less irregularly over the body, but there is no absolute 

 rule, and patches of new pelage may appear on any part of the 

 body, especially if the old coat has been thinned by abrasion or 

 other local cause" (p. 30). However, it appears that certain 

 other students of the genus do not find the process of moult as 

 irregular as described by Nelson. 



According to Barrett-Hamilton ('12), the order of change in 

 the European hares, though not invariable, generally follows a 

 fairly regular sequence. In the autumnal moult, the feet and 

 legs, the gray parts of the ears and parts of the head are first 

 to undergo the change. Then follows the rump, and the white 

 area of the ventral surface gradually creeps upward on the sides 

 until the brown of the summer coat is extinguished or remains 

 as a "small island or islands." In the spring the sequence and 

 directions of growth are completely reversed, the new pelage 

 appearing first on the head and median dorsal region, growing 

 downwards. This same reversal is described by Allen in his 

 paper on the changes of pelage of the varying hare (Lepus ameri- 

 canus) . 



