170 



Bulletin American Museum of Natural History. [Vol. XXVII, 



The Marsupial affinities of the Multituberculates thus seem to be fairly 

 well settled, but as to their being true Diprotodonts the writer cannot yet 

 feel certain for the following reasons: (1) because so far as indicated by 

 Marsh's All od on fort is the enlarged incisor in ^Multituberculates is i", whereas 



Fig. 8. Skull and lower jaw of Polymastodon taoensis Cope. Skull, Amer. Mus. No. 3075, 

 reconstructed by Dr. W. D. Matthew; lower jaw composition from Amer. Mus. Nos. 968 and 

 748. X |. 



in Diprotodonts it seems to be i^ {cf. Weber, 1904, p. 339, fig. 263); (2) 

 because the Multituberculates differ greatly from the true Diprotodonts in 

 the characters of the cheek teeth; (3) because homoplastic resemblances, 

 especially among related groups, is so frequently shown in the dentition. 



The Orders Triconodonta and Trituberculata. 



Historical Develo'pment of the Classification} 



1814 ? Two small fragmentary fossil jaws (later made the types of Amphi- 

 therium prevostii and Phascolotherium hucklandii) are brought to 

 Mr. W. J. Broderip from Stonesfield Slate (Middle Jurassic) near 

 Oxford. 



1824. Dr. Buckland announces the discovery of the remains of Mesozoic 

 mammalia in his paper 'On Megalosaurus.' 



1 The early liistory of the discovery of Mesozoic nuunnial remains is sketclied by Goodrich 

 (1894, pp. 409-412). 



