PIED DU DIPROTODON. 277 



On the other liand, regarding thc feet. as a whole, thoy, in tlieir 

 shapo and proportions as well as in the characlor and dogrec of thc 

 attonnation of llie second and third digils 6f thc pes, are more 

 readily comparable lo thèse members in the Phascolomyidse. 



With the more specialised pes of the Macropodidse comparison of 

 Ihat oi Diprotodon yieldsscarcely any points of rcscmblance except 

 in so far as the character of the dégradation of thc hind feet — 

 similar in kind but varying in degrec — afîords évidence of the 

 marsupial nature of both. 



Thus the conclusions as to the generalised characters of 

 Diprotodon, which hâve been reached through other parts of the 

 skeleton, are confîrmed by the structure of the feet. » 



« In the remaining portions of Iho pes thc dégradation of the 

 hind-foot, characteristic of the Diprotodont group of thc Marsupialia 

 and of the Peramelidse amongst the Polyprotodonts, becomes 

 évident in the atténuation of the second aud third digits — particularly 

 of the second — and, to a Icss marked degree, of thc plialanges of 

 the fourth, as well as in the réduction of the hallux to the metatarsal 

 only. This degrec of diminution in thc size of thc parts corresponding 

 to the second and third digits, tliough relativcly more considérable 

 than that which obtains in Pluiscolomys, falls short of the 

 symmetrical and almost fîliform atténuation to which tliey are 

 reduced in the Macropodidse ànd Pcramelidse. 



In view of the syndactylism which is corrélative with the 

 réduction in size of the two digits in those marsupial familles in 

 which tliis condition exists, it is reasonable to suppose that it 

 existed also in Diprotodon. » 



« What has been said of the limitations of function imposed 

 upon the manus by the collective feeblcness of its digits, applies 

 with even grcatcr force to the pes, in which thc fealure of digital 

 inefficiency is still more cxpresscd oither by extrême atténuation or, 

 as in the hallux, by réduction of parts. Indeed it is diftîcult to 

 imagine to what spécial use such digits as thèse might hâve been 

 put. » 



VI. — Il résulte de ce qui précède : 



1. Que MM. Stirling et Zietz retrouvent bien dans le pied du 

 Diprotodon des caractères marsupiatccc, mais qu'ils ne s'expliquent, 

 ni sur la signification^ ni sur l'origine de ces caractères. 



