1897.] NATURAL SCIENCES OF PHILADELPHIA. 37 



THE HANDS AND FEET. 



The nails of both hands and feet, with the exception of those of 

 the second and third toes, are almost entirely concealed by epi- 

 dermis. They are, indeed, mere scales, which apparently represent 

 the lowest possible phase of development. Those of the feet are 

 as in the hands, excepting those of the second and third toes. 

 The well-known prorect claws have been aptly compared to thorns 

 on a rose bush. They stand at an acute angle to the sharply flexed 

 second phalanges and permit the broad toe-tips to project to a 

 greater extent than in other toes. I venture in this connection to 

 make a suggestion as to the use of these claws. They are fur 

 dressers and parasite searchers for the head and shoulders. It is a 

 matter of common observation that ecto-parasites are prone to fix 

 themselves about the face and ears. A palmate-finger-tipped animal 

 would be placed at a disadvantage at the toilet. It is probable 

 that when the claws are in use the fourth and fifth fingers are 

 flexed. 



The palmar callosities are marginal to the thenar and hypothenar 

 eminences. The basal pads in the digits are large — one is proper to 

 the fourth digit. Burmeister simply states concerning the two basi- 

 digital pads that they lie at the base of the middle and following 

 finger. 



In the foot the hallucal and hypothenar pads are strictly margi- 

 nal. They join at the wrist. A metatarso-phalangeal pad lies axial 

 to the third digit. A large pad lies axial to the phalanges of the 

 hallux. It projects into the first inter-digital space and is well dis- 

 played when this space is defined from the dorsum. All three pads 

 are in effect callosities to the metatarsal and the metatarso-phalangeal 

 joints except the first, which overlies in part the powerful Adductor 

 pollicis. 



The pad of the first toe is opposed to that of the fifth toe. The 

 manner of insertion of the Adductor pollicis would naturally have a 

 tendency to pull the entire digit to the ulnar border while flexing 

 the phalanges. The location of the tendon is seen without dissection. 

 The hallucal pad overlying this muscle in part is an interesting 

 structure. This portion of the manus and pes in mammals generally? 

 so far as I know, is free from callosities. But in T. fuscus the pad 

 is the largest in the foot and projects toward the sole so as to sug- 

 gest an important function in grasping. 



