BY C. W. DE VIS. 237 



have to be substantiated by further and, as it appears to me, more 

 conclusive evidence. Assuming its truth for the moment we must 

 accept the consequence, that the cave fauna, in which we are told 

 there appears an existing species (P. latifrons), is partially of later 

 origin. 



Phascolonus, Owen, is demonstrably a good genus, but the 

 ground on which it has been separated, namely, by identification 

 with Sceparnodon, a determination so improbable in itself that 

 nothing short of direct proof should suffice to give it currency, 

 appears to me quite inadequate, to say the least. Owen's suspicion 

 that this great wombat in skull and teeth might one day show 

 itself to be generically distinct from Phascolomys was a happy 

 conception, but it is not by means of the teeth and skull exclu- 

 sively that its differentiation may be proved. In each of the other 

 known parts of its skeleton there are departures from normal 

 phascolomine characters amply sufficient to determine the judgment 

 in favour of its separation from Phascolomys. It is unnecessary 

 to go into details to settle an undisputed question, but to anticipate 

 an objection which might be taken to proofs derived from isolated 

 bones in this and other cases on account of the uncertainty 

 attaching to their determination, it may be permissible to state 

 the process by which the identification of PhasColonus bones was 

 , ascertained. 



While taking measurements of the bones of a Phascolomys 

 platyrhinus for comparative purposes, it was observed that the 

 width of the distal end of the humerus corresponded very closely 

 with the length of the upper molar series, the millimetres being 

 5 4 '5 and 53*5 respectively. Naturally it seemed not impossible 

 that a similar equation might obtain in an extinct species. To 

 put the notion to the test search was made for a phascolomine 

 humerus which should be in width about equal to the length of 

 the series of upper cheek teeth in a P. gigas, namely, 105 mm. 

 The bone was fortunately discovered and found to measure 

 104 mm. It was then assumed with some degree of confidence 

 that twice the linear dimensions of P. platyrhinus might be 



