ON THE EXTERNAL CHARACTERS OF THE KOALA. 591 



33. The External Charactei's of the Koala (Phascolarctos) 

 and some related Marsupials. By R. I. PocoCK, 

 F.R.S., F.Z.S. 



[Received Maj' 10, 1921 : Read June 7, 1921.] 



(Text-figures 22-26.) 



Co]STENTS. Page 



Introduction 591 



The Rhinarium 594 



The Facial Vibrissse 596 



The Mouth 596 



TheEar 596 



The Fore Foot 599 



TheHindFoot 601 



ThePouch 604 



The Classification of existing Diprotodouts 606 



Introduction. 



The body of the female Phascolarctos described in the following^ 

 paper was veiy kindly sent to me by Mr. A. F. Richardson when 

 I explained to him the zoological importance of the animal and 

 the infreqnency with which fresh examples come into the hands 

 of anatomists in this country. 



The need for renewed examination of Phascolarctos is especially 

 shown by the disagreement amongst modern zoologists regarding 

 the position and status to be assigned to it in the classification of 

 Diprotodont Marsupials. Thomas, for instance (Cat. Marsupialia 

 and Monotremata in Brit. Mus. 1888), divided the suborder into 

 three families: (1) Macropodidpe with the subfamilies Macro- 

 podinfe/Potoroinse, Hypsiprymnodontinse ; (2) Phalangeridte with 

 the subfamilies Tarsepedinse {Tarsijies) , Phalangerinse {^Phalanger , 

 Trichosurus, Pseudochirus^ Petauroides, etc.), and Phascolarctinse 

 (^Phascolarctos) ; and (3) Phascolomyidte (^Phascolomys). 



In connection with the Macropodidae and Phalangeridse, Thomas 

 pointed out that the characters of Hypsiprymnodon are inter- 

 mediate between those of the two families, and render the division 

 between them by no means so sharp and well-defined as it has 

 been usually considered to be. Nevertheless, his arrangement 

 suggests that Phascolarctos is an aberrant member of the 

 Phalangeridse more nearly related t0 Phalanger than the latter is 

 to Macropus. 



Thomas's classification has been adopted by English zoologists 

 and by Trouessai-t in his Catalogue (1912). 



Bensley (Amer. Nat. xxxv. pp. 117-138 and 245-269, 1901; 

 and Tr. Linn. Soc. Lond. (2) ix. pt. iii. pp. 83-214, 1903) followed 

 Thomas in admitting the family Phascolomyidse and in regarding 

 Phascolarctos as the representative of a subfamily of the Phalan- 

 geridje ; but he made the important modification of transferring 



Proc. Zool. Soc— 1921, No. XL. 40 



