1 900.] HAIR-SLOPE IN CERTAIN MAMMALS. 677 



same direction of slope of hair in this region as Man. From this 



I was led to suggest that the direction in question is due to 

 pressure of the weight of the fore part of the body acting 

 downwards and forwards, and that the resultant of these two 

 forces, in the cases of Carnivores and other animals accustomed to 

 a " couchant " attitude when at rest, would tend to direct the slope 

 of the hair away from the manus on the extensor surface of this 

 limb-segment. As a matter of fact this slope is found in nearly 

 all Carnivores, wild and domesticated, in which the hair is short 

 enough to allow of its observation. On the other hand, in most 

 Ungulates one finds that the slope on this extensor surface does 

 not present the reversed curl of hair found in Carnivores and 

 Primates. This rule is far from universal : e. g., the Elk, Domestic 

 Horse, and 4 Antelopes present on this limb-segment, over the 

 distal fourth, a slope towards the radial border ; and further, 



II Antelopes and 20 Cervidse examined have a slope hardly differing 

 from that of Carnivores (see subsequent remarks, p. 686). From 

 this basis of fact 1 suggested that the hair-slope in Ungulates 

 assumes this direction, which is more in accordance with the general 

 slope of hair in other regions of the limbs, and so differs from that 

 of Primates and Carnivores, because of the attitude assumed by 

 Ungulates when at rest. These animals so commonly rest with 

 the extensor surface in question resting on the carpus and manus 

 in flexion, in other words with the fore-limb doubled underneath 

 the body, that any pressure downwards on this area of hair serves 

 only to confirm its manus-ward slope, there being no horizontal 

 force acting with the vertical to produce a forward slide, as must 

 always be the case in the " couchant " attitude of Carnivores. 



Following up this point, in ' Natural Science,' Nov. 1897, 

 p. 357, I made a short note of the bearing of these facts on the 

 doctrine of the non-inheritance of acquired characters. 



This matter has now been investigated somewhat further in a 

 different region of the bodies of hair-clad mammals, namely, 

 the frontal, nasal, and premaxillary areas. I find among the 

 different mammalian orders some singular divergences in the 

 arrangement of this hairy surface. Here is a part of the body 

 very much open to inspection, and one which from its prominent 

 position must be subject to the action of tolerably constant 

 external forces, differing necessarily in different forms, according 

 to their environments. 



It is not possible to understand enough of the daily lives of many 

 of the animals referred to below, but of some we may claim to know 

 certain forces which cannot but act upon them in certain directions. 

 A few of these will be considered later. 



The most common hair-covered mammals occur among Primates, 

 Insectivores, Carnivores, Ungulates, Rodents, Marsupials, and 

 Monotremes. 



The great majority of these conform to a certain general distri- 

 bution and slope of the hair in this region of the head. This 

 slope ordinarily commences in the premaxillary area just above the 



