BY H. H. SCOTT AND CLIVK K. LORD. 3 



"Diprotodontidfe. ... It is easy to sea how the structure of 

 "the cheek teeth could pass into that of the Phascolomyidse; 

 "and it is not improbable that the two families may have 

 "diverged from a common ancestor." (3) (1887, Vol. 5.) 



That was our thought at the time of writing, and Mr. 

 Longman's association of these jaws, almost immediately 

 afterwards, with a more aberrant type of cranium than 

 anything that had hitherto come to light, shows that our 

 diagnosis was not misplaced. 



Anybody who will carefully read our notes cannot fail 

 to see how highly we estimated De Vis' work, and we regret 

 to stand charged with any unfairness to him. We, there- 

 fore, take the first opportunity of saying that nothing was 

 farther from our thoughts. Our general perusal of De Vis^ 

 works left the definite impression upon our minds that he 

 looked to Sceparnodon to clear up some outstanding puzzles 

 in regard to these generalised creatures, of which (as the 

 future may yet prove) he visualised at least eight groups. 

 In effect our reference simply meant this — Sceparnodon, hav- 

 ing been shown by Stirling to be a synonym of Phascolonus, 

 was eliminated ipso facto as a possible generalised animal, 

 and this, in our opinion, left its generalised connection to the 

 Wombat stirp pure and simple. Unfortunately (so hard is 

 it to kill "genus," "species," and "variety"), the word "genus'^ 

 crept in here, although the wider sense of the word is quite 

 manifest when the sentence enclosing it is taken in con- 

 junction with the full context. 



Mr. Longman's criticism therefore pivots upon the single 

 word "genus." Nature never produced animals ready made 

 to genus, species, or variety, although she may have pro- 

 duced them in groups, and we yet hope to see these Noto- 

 therian groups with their sex, age, and individual variations 

 clearly defined. 



As, however, this was not a fait accompli when our notes 

 were in course of compilation, and very much printer's ink 

 had already been used over the dentition by those who had 

 gone before us, we decided to seek the eff'ects produced by the 

 super-imposition of the Rhinoceros trend upon this section 

 of the Marsiipialia, rather than re-list the variation of the 

 premolars; some of which mutations are dangerously close 

 to the morphological minutiag inseparable from diphyodont 

 succession. That any marsupial group should have taken 

 on the Rhinoceros trend would, in the fact itself, introduce 



(3) Lydekker. Cat. Fossil Mammalia, Brit. Mus. Vol. 5, 1887. 



