260 Mr. C. W. De Vis on Nototlieriura and Zygomaturus. 



apparent shortness of tlie tooth ; but this again is also partially 

 due to absorption of the posterior basal talon resulting from 

 pressure in the rear. In short, the tooth before me is nothing 

 but the somewhat mutilated, some\diat abbreviated, and some- 

 what disguised homologue of its fellow. Most assuredly it is 

 not tlie tooth of Notothermm as known to me. Such is the 

 ground, treacherous in itself and sadly misunderstood, which 

 allowed my critic to sink into a veritable slough of surmise. 



To my question respecting the maxillary fossils which 

 occur in frequency corresponding to that of the numerous 

 mandibles of undoubtedly Nototherian origin, ]\Ir. Lydekker 

 responds somewhat inconsiderately to the effect that these 

 " crushed Di^yy-otodon-like skulls " (all these terms are his own 

 and unwarranted) may indicate " young individuals or a small 

 species of Diprotodon itself." If this be so, nothing remains 

 for me but to unlearn and relearn, if possible, the means of 

 distinguishing between old and joiing Dipi'otodonSjOr, perhaps, 

 in course of time to describe a " small Diprotodon " with its 

 posterior incisors on the edge of the jaw. 



This would not be a difficult feat for one prepared to 'say 

 that Oicenia is probably a " small form of Nototheriumj'' that 

 is of Zygomaturus^ since in Mr. Lydekker's judgment a form 

 with reduced dentition, small narrow nasals, elongated muzzle, 

 and slender jugals may be one generically with a form anti- 

 thetical to it in these and many other respects. Mr. Lydekker 

 has very liberal ideas of the amount of differentiation some- 

 times required for the establishment of a genus. 



With respect to the name Oioenia, Mr. Lydekker remarks 

 that it is preoccupied three deep in the Invertebrates, leaving 

 it to be inferred tiiat this also is a discovery of his own ; it is 

 a distinct act of unfairness (unintentional I should be willing 

 to think) not to state that I called attention to the fact while 

 pleading that under the circumstances the name might be 

 accepted. 



Minor blemishes, such as terming my rejoinder to his foot- 

 note in the B. M. Cat. of Foss. Mamm. a reopening of the 

 question, I pass over, with merely a word on the " untenable 

 proposition," which proposition briefly is that when a type 

 lacks a requisite characteristic that one of the proposer's 

 cotypes which does possess the characteristic required should 

 for practical purposes be taken as the typical example. This 

 seems to me to recommend itself to common sense. It may 

 be observed that Mr. Lydekker himself holds the untenable 

 by resting his case not on the molars of the type, but on the 

 shape of the premolar deduced from that of the cotype. 



On the whole I have to thank Mr. Lydekker for his criti- 



