388 



MK. R. I. POCOCK ON THE EXTERNAL 



quite smooth on its postpollical portion. The hind foot is also 

 like that of Octodon, but is relatively broader and shorter, being 

 actuall}' broadei', instead of nariower. than the fore foot. More- 

 over, the hallucal or inner element of the plantar pad is not 

 fused with the metatarsal pad, but forms part of the plantar pad 

 itself, which is thus four-lobed instead of three-lobed as in 

 Octodon, and there is no trace of divisional line on the meta- 

 tarsal pads, and there are no enlai'ged papillae either on the 

 plantar or metatarsal jDads. (Text-fig. 9, C, D.) 



Text-figure 11. 



1'- 



e. 



A. Right hind foot of JErethizon dorsatum. 



B. Right fore foot of Coendu preJiensilis. 



C. Right hind „ „ the same. 



hallux ; c, heel ; e, prehensile expansion of sole. 



Except that they are broader and shorter, with shorter digits, 

 partially webbed basally, much longer claws, and the component 

 elements of the plantar and carpal pads less clearly defined, 

 the feet of Erethizon are like those of Capro'mys. The above- 

 mentioned differences, together with the suppression of the 

 pollex, externally attest higher specialisation of the feet, in 

 accordance probably with greater adaptation to arboreal life. 



