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Show 368 DR. H. GADOW ON THE SYSTEMATIC [May 3, The tooth formula of Notoryctes differs consequently from that of all other known Polyprotodonta in the smaller number of incisors, namely | against = in Didelphidce, g in Peramelidce, and ^ in Dasyu-ridce; while the number of premolars, -2, agrees with that of Dasyurus against Didelphidce, 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 of Notoryctes. Specimen A f Incisors. Specimen B \ Specimen C \ Male I. Male II ] I Male V | Female I •! Female III Female IV + + + + + + + + + + + + + + + + 0. Premolars pm. 1 pm.3 0 + + + + + + + + + + + + + + * 0 0 0 * 0 0 + 0 0 0 0 8i9 10 Molars. + + + + + + + Pm. 1 small. Pm. 1 small; canine absent. Pm. 1 small. C. and pm. 1 absent. C. and pm. 3 absent. Pm. 3 small. Pm. 3 absent. Pm. 3 absent; canine small. Pm. 3 small. C. and pm. 3 small. Pm. 3 absent. 0. small, pm. 3 absent. Pm. 1 small. C. small, pm. 3 absent. C. small, pm. 3 absent. C. small, pm. 3 absent. C. small, pm.3 absent. I. 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 |
