1881.] MR. W. A. FORBES ON THE KOALA. 193 



limbs are equal, the tibia and fibula are widely separated, excepting, 

 of 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 ligamentum 

 teres', 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 P/ialangista, 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 jjremolars which, 

 in the typical Phalaugers, intervene between the canine and the five 

 molars of the upper jaw, and the incisor and the corresponding 

 teeth in the lower jaw." Dr. Murie, from his examination of the 

 osteology of the Wombats (P. Z. S. 1867, p. 815), appears also to 

 incline to Mr. Waterhouse's view. 



In the course of this paper I have already noted several other 

 points of resemblance between the Koala and Wombat, in the 

 presence in both of more or'less distinct cheek-pouches, in the absence 

 of a distinct caudate lobe to the liver and the tendency of its lobes 

 to develop additional superficial sulci, and, finally, in the structure of 

 the female reproductive organs. In the Wombat, too, the first 

 traces of the syndactyle condition of the pes appears, both exter- 

 nally and also in the structure of the bones. But, to my mind, the 

 most convincing token of their affinity is their possession of the 

 peculiar gastric gland ^ already referred to and described. In no 

 other Marsupial is there any trace of such a structure visible, whilst 

 in the two forms under consideration its identity is almost precise. 

 That such a unique structure should have been independently de- 

 veloped in two forms unrelated to each other appears to me to be in 

 the highest degree improbable. 



The main points of divergence from the Phalangers presented by 

 the Wombat are the peculiarities of its dentition, and its extra- 



1 I suppose by this is meant as opposed to the sacculated stomach of the 

 Kangaroos. 



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

 character practically common to all Marsupials, excepting the PerameUdse 

 ((■/. Flower, ' Osteology of Mammalia,' 2nd ed. p. 306). As regards the alleged 

 absence of a ligamentum 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. 



^ It would be interesting to investigate the histological structure of this 

 gland, with the object of determining whether or not the resemblance is more 



an external. 



Proc. Zool. See— 1881, No. XIII. 13 



