EXTERNAL CHARACTERS OF THE KOALA. 601 



clearly seen even on dried skins ; and it is shown in the figures 

 of the Spotted Cuscns in the Royal Natural History, iii. p. 257, 

 1894, and Harmsworth's Natural History, ii. p. 888, 1910. 

 These figures bear the impress of having been drawn from life by 

 Miitzel and Kuhnert respectively. 



The fore foot of Pseudochirus resembles tolei-ably closely that 

 of Phalanger^ except that the third digit is not lengthened and 

 the lobes of the plantar and carpal pads are sef)arated and smaller, 

 the fused pollical element of the plantar pad and the inner moiety 

 of the cai'pal pad forming an oblique transverse mass about twice 

 as wide as long. 



The fore foot of Phascolarctos is an extreme exaggeration of 

 the ty^^e seen in Phcdanger and Pseudochirus, although the pads 

 and intervening spaces are areolated or granular, not striated. 

 The sole is much longer as compared with its width : the first 

 and second digits are completely isolated from the rest, and rise 

 close together from the postero-internal angle of the foot, at I'ight 

 angles to its long axis and close transversely across the proximal 

 half of the sole, the posterior border of the pollex when drawn 

 back being approximately in the same transverse line as the 

 posterior border of the sole. There is a large three-lobed plantar 

 pad at the base of the third, fourth, and fifth digits, and there is 

 a similar but smaller lobe upon the base of each of the second 

 and first digits. The one on the pollex probably represents the 

 inner moiety of the carpal pad, and the one on the base of the 

 second digit the first or external element of the plantar pad, 

 widely severed from the lobe in front of it and altogether discon- 

 nected from the pollex behind it. The external moiety of the 

 carpal pad is small, restricted to the postero- external angle of 

 the foot and widely separated from the plantar pad. 



In Phascolomys the fore foot, modified for terrestrial progres- 

 sion and digging, is very different from that of the pi^eceding 

 genera, especially from that of Phascolarctos. It may be derived 

 from the type seen in Trichosttrus by the shortening and widening 

 of the digits and sole, the obliteration of nearly all trace of the 

 individual elements of the pads, a.nd by the straiglitening, 

 lengtheiiing, and blunting of the claws. 



2V;e Rind Foot. — In Trichosurus* , Phalavger, and Pseudochirus 

 there are one or two tactile vibrissa, similar to the carpal vibrissa?, 

 on the inner .side of the heel behind the hallux. These are 

 absent in Phascolarctos and Phascolomys. 



The hind feet of the four arboreal genera- — Trichosurus, 

 Phalanger, Pseiulochirus, and Phascolarctos — differ from each 

 other much less than the fore feet. Their general structure is 

 well known. Hence only the comparatively minor points of 

 difference need be noticed. 



* Kepresented in the figure of the hind foot of Pseudochirus cooki (pi. 20. fig. 4, 

 of Waterhouse's ' Marsupiata '), but apparently unnoticed in the text. 



