OF THE AUSTRALIAN MAKSUPIALIA. 175 



fact that P. Coclcerelli is very closely related to P. Dor ey ana, and that the latter, together 

 with P. Raffrayaim, are the most priniitive forms in dentition ; also that all three are 

 Papuan in their distrihution. The foot-patterns of the Australian or mainland forms 

 are traceable to that of P. Haffrayana. These species present a division into short- and 

 long-footed series : the former including P. macrura, P. oheswla, and P. barrowensis ; the 

 latter P. Bougainvlllei, P. nasuta, P. Gunnl, Thylacomys, and Choeropus. In the long- 

 footed series development has probahly proceeded along three suhsidiary lines. 



In P. CockerelU (PI. 7. fig. 14) we find a very close approximation to the typical 

 condition in the Phalangeridae. The foot is comparatively short ; the proportion of 

 hreadth measured immediately hehind the hallux to the length measured from the 

 heel to the tip of the fourth digit, excluding the claw, is approximately 1 : 4"3. It is not 

 possible to make a similar measurement of a phalangerine foot, hut it may he observed 

 that if the foot of P. Coclcerelli were provided with a well-developed instead of a reduced 

 opposahle hallux, its proportions Avould he almost exactly as in the Phalangeridae. In 

 other words, the plantigrade and non-elongated condition has been perfectly retained. 

 P. CockerelU is specialized after the manner of all other secondarily terrestrial forms in 

 the reduction of the opj)osable hallux. It is primitive, as compared with other Pera- 

 melidae, in the more radiate arrangement and greater freedom of the outer digits, this being 

 a phalangerme character which is lost in the more advanced forms. Another primitive 

 character is observable in the jiosition of the notch separating the conjoined second and 

 third digits from the fourth on a level with that separating the latter digit from the 

 fifth. Of the plantar pads characteristic of the arboreal type of pes, only the digital 

 elements are represented ; they are well separated, but have no striated areas, their 

 surface being granular like the rest of the sole. The claws of the fourth and fifth digits 

 are slightly curved : this is also a primitive character — in the more specialized sub- 

 digitigrade forms the claws are stouter and also straighter. 



The above description of P. CockerelU applies almost equally to P. Doreyana. In 

 P. Raffrayana (PL 7. fig. 15) the pes is more specialized in its proportions, the ratio of 

 breadth to length in a specimen measured being 1 : 63. The hallux, howevei*, is almost 

 better developed, its proximal phalanx and metatarsal being quite large. The plantar 

 pads are also more primitive. At the base of the hallux there is a small elevation 

 representing a hallucal pad, the apex of which bears a smooth area, probably representing 

 a formerly striated surface. The digital pads are well developed and show the same 

 characters as the hallucal one. 



In P. moreshyensis we find much the same characters as in P. Haffrayana. The 

 proportion of breadth to length in a specimen measured was found to be 1 : 6'1. The 

 hallux is more reduced. There are no signs of a hallucal pad and the first digital pad is 

 obsolete. The second and tliird digital pads are well developed, but their apical smooth 

 areas are not so well marked. Practicallv the same characters are found in P. obesula. 

 The proportion of breadth to length in a specimen measured was found to be 1 : 6'3. 

 A dried preparation of P. macrura showed a proportion of 1 : 7'5, but this measurement 

 cannot well be compared with those of spirit-sj)ecimen3. 



The species just referred to are essentially short-footed forms. In the remaining ones, 

 with the partial exception of the annectant form P. nasiita, the pes shows definite signs 



