20 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. XIV. 



The upper lips have a thin coriaceous edge that continues to the 

 median sulcus which partially divides the rhinarium and forms an 

 incipient cleft of the lips. The lower lips have a similar narrow edge 

 which is only very slightly thickened in front. The lower lip is free in 

 front from the base of the long incisors and has a high internal median 

 ridge or frenulum which fits into the slight space between the incisors. 

 Slightly in front of the angle of the mouth and just in advance of the 

 molariform teeth is a pair of reciprocating labrets or outgrowths of 

 the lips, one on the upper and the other on the lower lip (PL II, fig. 2). 

 These appear to be an adaptation for the ejection of undesirable food 

 particles during mastication. They are directed slightly outward and 

 downward in such a way that with the lips wholly or partly closed in' 

 front they might in conjunction with the buccinator muscle serve to 

 guide hard parts of insects or other matter to the exterior. A quite 

 different function also is possible, that is, in closing the lips at this point 

 and assisting in isolating the internal cheek pouch formed by the 

 buccinator muscle. This pouch is fairly definite and includes a consider- 

 able space laterad of the molariform teeth. 



Tail. The tail is gently tapering and has no inordinate thickening at 

 the base. The body fur extends upon it only a very slight distance. 

 Thence to the tip it is thickly set with short stiff hairs which nearly or 

 quite conceal the underlying scaly annulations. At the tip there is 

 usually a slight hairy pencil. Nothing suggests prehensilism in the 

 slightest degree. 1 The contour of the tail is rather distinctly quadri- 

 lateral instead of cylindrical. 



Feet. The fore feet are pentadactyl, but the outer toes are decidedly 

 reduced and furnished with small blunt nails instead of claws. The 

 third or middle toe is slightly the longest and the second and fourth are 

 subequal, all three bearing sharp curved claws. The reduction of the 

 lateral toes and especially the absence of claws is in marked contrast to 

 the condition general among Dasyuridae and Didelphiidae but is almost 

 exactly paralleled in the Peramelidae in many of which the reduction 

 of the first and fifth toes has proceeded much farther. In Canolestes, 

 however, although the elongated middle toes seem to indicate a digiti- 

 grade adaptation, the plantar surface is carried well backward on the 

 outer side and supported by an unusually large pisiform bone. There are 

 five plantar pads well distinguished from each other and having smooth 

 non-striated surfaces. 



The hind foot is relatively long and narrow. Its general proportions 



'Thomas (1895), in describing C. obscurus, states that the tail has "its termina 

 inch below wholly naked" and that "it is therefore presumably prehensile." Nc 

 such condition has been observed in other specimens and it is probable the tail in th< 

 above-mentioned one was abnormal. 



