186 ON THE ANATOMY OF THE KOALA. 



did so with some hesitation. He says (7. c. p. 16) : " Upon a careful 

 examination of the Wombat, I find so many points in common with the 

 Phdlangista group, that it is so intimately connected with the Koala 

 (which is more clearly an aberrant Phalanger), as indicated by the struc- 

 ture of the stomach and the deficiency in the number of the false molars, 

 and the total absence of tail, that I am inclined to regard the genus Plias- 

 colomys as presenting an aberrant form only of the Phalangistidse. That 

 the thumb should be reduced to a small size in this animal, which differs 

 from others of its (supposed) family in living upon the ground, I am 

 prepared for, since in the Dasyuridse the same thing takes place under 

 similar circumstances. I am also prepared to find in an herbivorous 

 group like the Phalangistidae a difference in the structure of the molar 

 teeth, in haying them rooted in one case and rootless in another, for 

 such happens in other herbivorous groups of the Mammalia." Again, in 

 a note on p. 257 : " With regard to the position of the Wombat and 

 the Koala (Phascolarctos) in a natural position, I may observe, in the 

 first place, the Wombat (cceteris paribus) shows some affinity to the 

 Phalangistidse in the possession of a thumb, which, though short, is very 

 broad and sufficiently distinct. Then, beyond this, we have to add that 

 P. Z. S. 1881, the limbs are equal, the tibia and fibula are widely separated, excepting, 

 p. 193. o f course, at the extremities ; and the stomach is simple *, as in the 



Phalanger group. On the other hand, we perceive in the Koala an 

 animal possessing all the essential characters of Phalangista, but in 

 which the stomach is provided with a peculiar glandular apparatus, and 

 the tail is wanting, as in the Wombat. The two animals agree, moreover, 

 very closely in the structure of the humerus ; they agree in the non- 

 possession of a patella, in the absence of a liyamentum teres f, and in the 

 outermost of the articular surfaces of the upper extremity of the tibia 

 being continuous with the articular surface of the fibula. The skull of 

 the Koala, as compared with that of a typical Phalangista, differs in 

 having the posterior palatine openings confined to the palatine bone, 

 which is also the case in the Wombat; the lower jaw differs in the 

 greater extent of the symphysis menti ; and, lastly, an approximation to 

 that Rodent-like type of dentition which is exhibited by the Wombat is 

 perceptible in the Koala, in the smaller development of the posterior 

 incisors and canines of the upper jaw, and the total absence of any of 

 those premolars which, in the typical Phalangers, intervene between the 



* I suppose by this is meant as opposed to the sacculated stomach of the Kangaroos. 



t As regards these last two characters, it must be observed that the first is a 

 character practically common to all Marsupials, excepting the Peramelidse (cf. Flower, 

 4 Osteology of Mammalia,' 2nd ed. p. 306). As regards the alleged absence of a liga- 

 mentum teres, I find it perfectly well developed in fresh specimens of both Koala and 

 Wombat; on the femur the depression for it, though not distinct, is traceable. 



