OF THE AUSTEALIAN MAESUPIALIA. 99 



is as functional in the carnivorous forms as in tlie insectivorous prototypes. The 

 explanation of this apparently anomalous condition is douhtless to be sought in the 

 progressive increase in the functional value of the canines. In the insectivorous forms 

 the latter teeth are at most only moderately developed, so that the premolars possess 

 their full functional value as grasping and piercing organs. In the carnivorous forms 

 these functions become largely usurped by the enlarging canines, and the incisors 

 and premolars become reduced. In Sarcoplulns and Dasyiwits the premolars present 

 an appearance as if the material formerly used for their development had been utilized 

 in the development of the canines. 



Mykmecobiin.e. 



The dentition of the single representative of this subfamily is of great interest on 

 account of its marked departure from the usual conditions in the recent Mammalia, in 

 respect to the peculiar cliaracters and extraordinary number of the molar teeth, and the 

 alliance thereby suggested between Myrmecobms and the Mesozoic Mammalia. 



It is a noteworthy coincidence that the original description of Myrmecohiiis by 

 Waterhouse (1836) was published only shortly before a vigorous discussion, marked by 

 the oj)inions of such eminent zoologists as de Blainville, Owen, and Agassiz, took place 

 as to the nature of the first of the famous jaws from the Stonesfield Slate. The 

 discovery of Myrmecohiiis, with its peculiar dentition, furnished Owen (1836) with a 

 strong argument in favour of the view that their affinities were not only mammalian, but 

 also marsupial. Owen repeated his opinion in his subsequent jiublications (1846, 1S71), 

 and even went so far in his estimation of the primitiveness of Myrmecohius as to suggest 

 a community of dental characters between it and the theriodont reptile Galescmnis 

 (1887). Following Owen, Thomas (1888, ^. 312) has characterized Myrmecobiits as an 

 "unmodified survivor from Mesozoic times," and its possible affinities have been 

 commented upon by other writers in almost every case in which the Mesozoic mammals 

 have been described. 



NeAv interest has lately been added to the question thi'ough the discovery by Poulton 

 of the true teeth of Omithorhynchus, the patterns of which were compared by that 

 writer (1888, p. 20) with those of Myrmecohius, and by Cope (1888, p. 2o9) with those of 

 the Multitubcrculata. Following Poulton's comparison, Leche (1891, p. 152) suggested 

 a possible community of type between the molars of the Multitubcrculata and those of 

 the Dasyuridse, through Myrmecohius, although he subsequently (1893, p. 114, footnote) 

 withdrew his opinion as to the resemblances between Oniithorhyiichus and Myrmecohius 

 on the publication of Stewart's description (1891) of a specimen of the former animal 

 in the collection of the Iloyal College of Surgeons with more complicated teeth 

 than those in the specimens previously described by Poulton (o/j. cit.) and Thomas 

 (1889). 



Winge (1882, 1893) lias expressed the opinion that the relations of Myrmecohius are with 

 the Dasyuridse, the extraordinary number of the molariform teeth being in bis estimation 

 the result of a retention of the normally deciduous premolars. Leche (1891), however, 



SECOND SERIES. — ZOOLOGY, VOL. IX. 15 



