258 Mr. C. W. De Vis on Nototherlum awe? Zygomaturus. 



acknowledges that I am right in attributing to the Latter a 

 P"'- ^ triangular in shape, and is thus driven to admit that the 

 right tooth of this skull is not a Nototherium premolar. The 

 former admission he is ready to make probably because it 

 seems to enable him to deal the blow which, as he phrases it, 

 leaves me without a leg to stand on. He claims to have 

 discovered by careful examination a fact which eluded the 

 scrutiny and stultifies the judgment of Sir Richard Owen, 

 namely that the true premolar of the skull is not the right 

 but ihe left tooth, and this he asserts to be of the triangular 

 shape demanded. Can anything more be required to prove 

 that this skull is beyond doubt Nototherium ? — possibly, as we 

 may see later on. 



But first, What of the unfortunate tooth so ignomini- 

 ously dismissed? We are gravely instructed that this may 

 be: 1st, an abnormality ; 2nd, a pseudohomologue ; 3rd, a 

 deception ; 4th, a milk-tooth — verily a quartette of the most 

 volatile assumptions ever accruing from the resolution of a 

 " too, too gross " fact ! Grant the tooth an abnormality — 

 then, as it occurs again in the maxilla from which I have 

 figured it and a third time in a third example procured of 

 late, we are led by it to the reductio ad ahsurdum " constant 

 abnormality." If it be not homologous with its fellow of the 

 opposite side, which tooth of the opposite side is in reality its 

 homologue ?, in other words, which dilophodont tooth should 

 be made to pair off with this forlorn bunodont ? We ought 

 not to be left in the dark on so interesting a point. Is it an 

 " insertion " fraudulent or accidental "from another skull"? 



Then, in two examples at least we have evidence that the 

 deception was set afoot by some practical joker or mysterious 

 agency in the Drift period for the confusion of a latter-day 

 disputant. As to its being a milk-tooth retained to old age, 

 the age impressed upon the posterior molars, and that in a 

 family long known to have been without milk-teeth, very good 

 evidence indeed in support of such a notion must be forth- 

 coming before it is likely to be accepted. Moreover, it involves 

 another abnormality — milk-teeth and their successors are in 

 Marsupials always, I believe, of the same type, differing in 

 size, sculptural details, and, to a less extent, in shape, but 

 not in general form and plan of structure, for an oval tuber- 

 cular tooth to be succeeded by a triangular unicuspidate one 

 would certainly be an anomaly. But, to protect Mr. Lydek- 

 ker from this particular illusion in the future, I have resorted 

 to the crucial test, and, opening the maxilla at my disposal, 

 find no trace whatever of successional tooth or formative 



