114 



NOTE ON THE GENERA ZYOOMATURUS AND NOTOTHERIUM. 



Nototherium should not differ widely from that of Owenia. Hut 

 the tooth in Zygomaturus does differ widely, it is indeed of a dis- 

 tinctly different type — a type reminding one of the Protemnodont 

 type more than anything else. Its posterior two-thirds are occupied 

 by a longitudinal ridge on the outer side, and two tubercles on the 

 inner, the outer ridge and anterior tubercle being joined by a low 

 link over which passes the longitudinal sulcus dividing the ridge 

 from the tubercles. The anterior third supports a single large 

 tubercle or rudimentary lobe. Such a tooth has but scant affinity 

 with that of Owenia, and therefore is most unlikely to have paired 

 with the Nototherium lower premolar, cast as we have seen in the 

 same generic mould as the corresponding Owenia tooth. Were 

 every other upper premolar which could be rationally ascribed to 

 Nototherium absent, we should still be justified in deferring accept- 

 ance of the identification asserted until positive proof that the 

 apparent anomaly is a fact were forthcoming. 



But, happily, the contingency does not exist. Teeth in strict 

 accord with the anticipation shaped by Owenia are by no means 

 infrequent, and in their very number we may see a further reason 

 for rehabilitating Zygomaturus. 



In a large series of such fossils, from one and the same locality, 

 it is reasonable to suppose that related parts of the skeleton, notably 

 those of the head, wiil occur in fairly corresponding frequency. 

 This is certainly exemplified in the case of Diprotodon, the larger 

 Kangaroos, Wombats, and Thylacoleo. It would, therefore be an 

 unaccountable condition of things, or rather one to be accounted 

 for by an objector, if the numerous lower premolars of Notother- 

 ium were derived from the same generic entity as the Zygoma' urus 

 teeth, three in number, which are all that represent the dentition of 

 that genus in the Queensland collection — these teeth moreover being 

 the only recognisable Zygomaturus fossils in the series ; whereat 

 the Nototherium premolars, loose and in place, are accompanied as 

 might be supposed by still more numerous mandibular remains 

 deprived of them. 



.On the other hand, as we said, upper premolars referrible to 



