THE SQUIRREL 



651 



Lady pauses. Down come Squirrel 

 Number One's fore-paws. Thud, tluid ! 

 upon the bough. Thud, thud ! his hind 

 feet echo them. Another moment and 

 they are at grips. You see a whirl and 

 gleam of tails (silver-grey in the sunshine) ; 

 you see small branches flicker as they 

 touch them ; you see an inextricable 

 confusion of tree and sky and 

 Squirrels ; you see that this con- 

 fusion is falling ; and presently you 

 see that the combatants have 

 parted, each to a separate bough, 

 some twenty feet below their start- 

 ing-place. How do they do it ? 

 How can two non-winged creatures 

 fight on snapping twigs ? How can 

 one eye be kept on one's rival and 

 the other on a landing-place, or 

 even a second landing-place should 

 the first one fail ? 



In his excellent book on the 

 " Sense of Touch in Animals," Dr. 

 Kidd has pointed out a peculiar 

 feature in the papillary ridges of a 

 Squirrel's hand. Dr. Kidd holds 

 that arched, whorled, or looped 

 papillary ridges (such as occur on 

 human finger-tips) are specialised 

 types, and that longitudinal, oblique, 

 or transverse ridges are primitive 

 types. He holds, further, that the 

 chief use of both types is in con- 

 nection with the sense of touch, and 

 that their frictional use is sub- 

 sidiary. Other investigators, not- 

 ably Miss Whipple, hold that the 

 chief use of papillary ridges is frictional — 

 they serve, that is, to " rough " the hands 

 and feet. 



One would certainly expect to find 

 that a Squirrel's hands were specialised 

 to avoid side-slip, and that they would 

 also give some external indication of 

 hypersensitiveness of touch. So far, 

 however, as the papillary ridges are con- 

 cerned, they appear to have no obvious 

 specialisation. The ridges are few in 

 number and indefinite in form, the most 

 noticeable being those on the palms of the 

 hand, which radiate forward from the 

 proximal portion of each pad. This 

 arrangement is unusual, and by no means 

 self-explanatory. The pads, as can be 

 seen from the illustration on page 650, take 

 up such a large proportion of the palmar 



surface that its grasping area is practically 

 hairless. The soles of a Squirrel's feet, 

 however, in which the pads have oblique 

 ridges, and are much smaller in proportion, 

 are fairly well haired. These facts suggest 

 to me that in the case of a Squirrel leaping 

 from one slippery bough to another, the 

 take off is strengthened by the hairy, non- 



UNDER SURFACE OF SQUIRREL'S TAIL. 

 Showing the " banding " of the long hairs. 



slipping character of the soles of his feet, 

 while the landing is broken by the elastic 

 buffer character of the palms of his hands. 



For a " tactile sense of the position of 

 his body in space," the Squirrel must. I 

 think, depend on his vibrisscs — it is 

 unfortunate that we have no English 

 word to correspond with the German 

 Sinneshaar (sense-hair), for the structure 

 of vihriss(V is quite different from that 

 of ordinarv hair. 



The vihrisscB of the Squirrel, in addition 

 to being abundant on the muzzle, appear 

 over and behind each eye, and, farther 

 Ixack still, beneath the throat. The latter 

 position is by no means a common one. 

 He also has a growth of them in the neigh- 

 bourhood of his elbow joints (the reader 

 will remember something similar in the 



