6 THE SENSE OF TOUCH IN ANIMALS 



Ardea egretta. 



Aquila audax. 



Falco subtutes. 



Tinmmculus alaudarius or Falco tinnunculus. 



Corvus corax. 



The terminology employed in the following descriptions of the 

 macroscopical and microscopical studies of palmar and plantar 

 skin will most easily be explained by the accompanying simple 

 diagrams. These represent the hand and foot of an Azara's 

 opossum which is a Mammal low in ordinal rank though 

 relatively high in intelhgence and activity of habits. It possesses 

 a development of the leading structures of the hand and foot 

 which may well serve as a type for the study of higher Mammals. 

 Certain terms employed by Miss Whipple in her exhaustive 

 memoir * referred to elsewhere will be used as affording in- 

 telUgible and unobjectionable descriptions of the parts of the 

 hand and foot. 



Fig. 1 represents the hand and Fig. 2 the foot of a simple and 

 typical Mammal. The digits on each are called, D. 1, 2, 3, 4, 5, 

 beginning with the thumb, or pollex, of the hand and the great 

 toe, or hallux, of the foot. The terms ulnar and radial are used to 

 indicate the outer and inner border respectively of the hand, 

 and fibular and tibial to indicate the outer and inner borders of 

 the foot. The expression "outer" and "inner" are here used 

 for convenience of description though not properly apphcable 

 to the hand and foot of Man who forms an exception to all lower 

 Mammals, for in Man, the radial is the outer and the ulnar the 

 inner border of the hand in his usual upright position with the 

 palm of the hand directed forwards. However, with this ex- 

 ception no mistake need be made in the use of these two common 

 terms. In Man as well as the lower Mammals the terms, fibular 

 and outer and tibial and inner, apphed to the foot always corre- 

 spond to one another. Miss Whipple usefully divides the pads 

 or eminences of the ventral surfaces of the Mammahan hand and 

 foot into three groups which she illustrates in the case of Microtus 



* "The Ventral Surface of the Mammalian Chiridium." Inez L. Whipple, 

 1904. 



