HAIR AND UNDER-FUR 



cular arrangement of the individual hairs among mammals ; 

 they are not hj any manner of means scattered without order, 

 but show a definite and regular arrangement, which varies with 

 the animal. For instance, in an American Monkey (Midas), the 

 hairs arise in threes — three hairs of equal size springing from the 

 epidermis close together ; in the Paca {Coelogenys) there are in 

 each group three stout hairs alternating with three slender hairs. 

 In some forms a number of hairs spring from a common point : 

 in the Jerboa {Dipus) twelve or thirteen arise from a single hole ; 

 in Ursiis arctos there is the same general plan, but there is one 

 stout hair and four or five slender ones. 'I'here are numerous 

 other complications and modifications, but the facts, although 

 interesting, do not appear to throw any light upon the mutual 

 affinities of the animals. Allied forms may have a ^-ery different 

 arrangement, while in forms which have no near relationship the 

 plan may be very similar, as is shown by the examples cited from 

 Dr. Meijerle's paper. The groups of hairs, moreover, have them- 

 selves a definite placing, which the same anatomist has compared 

 with the disposition of the bundles of hairs liehind and between 

 the scales of the Armadillo, and which has led him to the view 

 that the ancestors of mammals were scaly creatures — a view also 

 supported by Professor Max ^A^e1)er,-' and not in itself unreason- 

 able when we consider the numerous points of affinity l>etween 

 the primitive Mammalia and certain extinct forms of reptiles.^ 



The hairs are greatly modified in form in different mammals 

 a,nd in different parts of their bodies. It is very commonly the 

 case that a soft under-fur can be distinguished from the longer and 

 coarser hairs, which to some extent hide the latter. Thus the 

 " sealskin " of commerce is the under-fur of the Otaria ursina of 

 the ISTorth. The coarser hairs may be further diiferentiated into 

 bristles ; these again into spines, such as those of the Hedgehog 

 and of the Porcupine. Again, the flattening and agglutination 

 of hairs seems to be responsible for the scales of the Man is 



^ " Bemerkungen fiber den Ursprung der Haare," Anat. Anz. 1893, p. 413. 



- See for this matter, p. 90. Dr. Bonavia has recently advanced {Studies in 

 Evolution, London, 1896) the somewhat fantastic vie-w that the pigment-patches 

 of Carnivorous and other manmials are a reminiscence of an earlier scaly condition. 

 There is no direct evidence that the primitive mammals were scaly, nor are the 

 Monotremata or Marsupials furnished with any more traces of such a con- 

 dition than are other mammals ; and they are the most lowly organised of existing 

 JIammalia. 



