B\ H. H. SCOTT AM) CLTVE E. LORD. 91 



It will bo remembered that in the type skull of 

 Zygomaturus, the two premolars are of unequal size, and 

 that De Vis and Lydekker debated this point with some 

 heat < 12 ', the latter always contending that the Zygoma- 

 turus skull manifested both kinds of premolars, claimed 

 by De Vis as generic characters, and that both could 

 not have been associates of the skull. With what we know 

 of Nototherian skull asymmetry, we are not too sure of 

 this, and even supposing that no mutilation of the smaller 

 one was responsible for its reduced size, we could yet 

 b ve a normal, and very well marked difference might 

 exist in the two premolars of a single skull. 



All of which tends to prove how unwise it is to 

 dogmatise over small dental variations, the more so when 

 a very slight fracture would remove the outer third of a 

 premolar, and so convert an oval and multituberculate 

 one into an elongated angular crown of no special com- 

 plexity. 



THE OTHER SIDE OF THE TAXONOMIC 

 QUESTION. 



As wo arc making every honest endeavour to eluci- 

 date the truth, and not attempting to bolster up any 

 special theory, we present the alt to the double 



group system of classification here adopted — namely, that 

 of a single species of Nototherium, with all variations, the 

 results of age and sex. 



We get at the outset the fact that the instinct of 

 Professor Owen led him to determine two good species — 

 mitchelli and victories, and although Lydekker regarded 

 the latter as a mere individual variation of the former, 

 both Queensland and King Island have yielded similar 

 specimens under conditions that certainly do not su 

 any such assumption as that just, cited. Neverthelet 

 a single species is contended for, this evidence must be set 

 aside, as also the following facts relating to this special 

 connection : — 



A. That De Vis found enough variation in the 

 victorice remains that came to his hand, to found 

 a genus upon, some of which was by admission 

 unsound, but the rest was supported by similar 

 variations observed in Tasmanian Notoiheria. 



(12) Ann. and Mag. Nat. Hist., 1889. p. 150. 

 H 



