66 THE SENSE OF TOUCH IN ANIMALS 



Sguirrel-like Phalanger. — The lowest species examined are 

 Marsupials, and it is seen that these forms display a pattern 

 more alUed to those of the monkeys than does the Insectivore, 

 Rodent, or Lemurs chosen. Thus the Squirrel-hke Phalanger 

 shows the common type of elhpse on the terminal phalanges 

 found in most of the monkeys ; five footpads, instead of the 

 six which are common to most Primates, and these are all 

 covered with well-marked papillary ridges. 



Hedgehog. — The Hedgehog, though not the lowest in ordinal 

 rank, shows the most rudimentary patterns of any form examined, 

 two of the digits being tipped with a few ridges, and the foot- 

 pads with irregular radiating hues like those of the Squirrel. 



Kinkajou. — Of all the earher species here described the 

 Kinkajou is the most interesting, for it shows on the same 

 digits and palmar and sole, rudimentary ridges merging almost 

 imperceptibly into the tesselated arrangement of the epidermis 

 which is so common in many lower mammals. This form is 

 arboreal, but its hands and feet appear to be used for walking 

 on boughs of trees rather than for prehension, this function 

 being exercised by its large prehensile tail. Thus the transition 

 from a tesselated surface to that of papillary ridges, as shown 

 in Figs. 7 and 8 is the more easily understood, especially as 

 the ridges on certain of the digits are imbricated in a distal 

 direction. These conditions point to the sense of touch being 

 highly important to the Kinkajou. 



Common Sguirrel. — The Common Squirrel has claw-Hke 

 digits with very long nails, and rudimentary pulps without any 

 papillary ridges in these regions, but they appear on the middle 

 and proximal phalanges ; the aborted pollex shows no ridges. 

 There are five footpads, but no other than the radiating papillary 

 ridges on the distal and more projecting margins of the pads. 



Lemurs. — Both the Lemurs described have patterns far below 

 those of the Marmoset and other monkeys. Though the apical 

 pads on the digits of hand and foot, and the palmar and plantar 

 pads are fleshy and well marked with ridges, these are the 

 only portions in which any resemblance to higher forms occurs. 

 It is noteworthy that on all the digits of the hand and foot 



