368 



DR. H. GADOW ON TflE SYSTEMATIC 



[Mays, 



The tooth formula of Notoryctes differs consequently from that of 

 all other known Polyprotodonta in the smaller number of incisors, 

 namely | against ^ in JDidelphidce, ^ in Peramelidce, and s in Dasyu- 

 ridce ; while the number of premolars, g, agrees with that of Dasyu- 

 rus against Bidelphidce, Thylacinus, Thylacoleo, Phascologale, some 

 Perameles, and Myrmecobius, in all of which the original fourth 

 premolar is still present. 



Variation of the Number and Size of .Teeth in the Lower Jaws oi Notoryctes. 



Specimen A 



Incisors. 



Specimen B \ 



Specimen C \ 



Male I ] 



Male II •! 



Male V. 



Female I. . . 

 Female III. 

 Female IV. 



Pm. 1 small. 



Pm. 1 small ; canine absent. 



Pm. 1 small. 



C. and pm. 1 absent. 



0. and pm. 3 absent. 

 Pm. 3 small. 



Pm.3 absent. 



Pm. 3 absent ; canine small. 



Pm. 3 small. 



0. and pm. 3 small. 



Pm. 3 absent. 



0. small, pm. 3 absent. 



Pm. 1 small. 



0. small, pm. 3 absent. 



0. small, pm. 3 absent. 



0. small, pm. 3 absent. 



C. small, pm.3 absent. 



1. 3 and c. absent, pm. 3 small. 



While it was easy enough to disprove the existence of any Mono- 

 trematous affinities in Notoryctes and to refer it to the Marsupials, 

 the question to which of the families of existing Marsupials 

 Notoryctes is nearest related is rather difficult. Mr. Ogilby prefers 

 to look upon it as an aberrant Polyprotodont, and he has based this 

 opinion on the character of the teeth alone, with this reserve that, 

 if canine teeth be absent (as he himself has suggested) it is not a 

 typical Polyprotodont, but a true link between the Monotremata 

 and Polyprotodonts. This reasoning is not quite obvious. If 



