Tertiary.'] PALEONTOLOGY OF VICTORIA. {Mammalia. 



Plates III., IV., and V. 



PHASCOLOMYS PLIOCENUS (McCoy). 



[Genua PHASCOLOMYS. (Sub-kingd. Vertebrata. Class Mammalia. Order Marsu- 

 piata. Pam. Phascolomidae.) 



Gen. Char. — All the teeth with long curved hollow bases, destitute of solid fangs ; incisors 

 \, canines g, premolars %, molars |. The incisors are scalpriform ; the molars, except the first, are 

 divided each into two nearly equal parts by a very deep inflection of the enamel on the outer 

 side, and a shallow inflection on the inner side in the lower jaw, and the deeper inflection on 

 the inner side in the upper series. Body short, thick ; tail rutUmentary ; head large, depressed ; 

 eyes and ears small ; legs short, nearly equal ; anterior feet, with five short stout toes, each with 

 broad solid little-curved claws ; hind feet with five toes, of which the inner one is very small, 

 without claw, and placed at right angles to the others, which have curved claws, hoUow below ; 

 the three middle toes joined. Confined to Australia in the recent and fossil state.] 



Description. — Mandible. Symphysis terminating on a line with the middle 

 of the anterior lobe of the 4th molar (M -) ; from anterior edge of incisors to hind 

 edge of alveolus of last molar, 4 inches ; length of molar series, 2 inches 2^ lines ; 

 from anterior edge of alveolus of first molar (D-*)to edge of incisor, 1 inch 8i lines ; 

 width of diastema between hinder lobe of second molars, 9|- lines, deeply concave ; 

 anterior molar (D ^) obliquely ellipsoid in section. Width of anterior transverse 

 diameter of the two incisors together, 7 lines ; thickness in opposite direction, 3 lines ; 

 so that the width of each does not exceed the length. Ectacrotaphyte cavity deep. 

 The coronoid is large, wide, and high, its anterior root arising from the alveolar 

 wall of the last molar (M^), and not of the penultimate (M'-^), as in P. Mitchelli. 



In size, in the backward extension of the symphysis, and in the 

 whole length of the dental series from edge of incisor to hind 

 alveolus of last molar, this species agrees with the living naked- 

 nosed Wombat,PAa5co/o??ij/5/)feifj/r/«'wM*(Ow.), of the same localities ; 

 but it is easily distinguished by the great size of the molar series, 

 these teeth being not only larger transversely, occupying a longer 

 fore and aft space, but extending so very much nearer to the edge 

 of the incisors as to afford an easy mode of discriminating the species. 

 The figures on our Plate V. illusti'ate this clearly. If a horizontal 

 line be taken across the upper part of the plate touching the edge 

 of the incisors of the shaded figures 1 and 2, which belong to the 

 P. pliocehus., and those of the outline figure 3, which is taken from 

 the living P. platj/rhinus, and if another line parallel to the first be 

 taken so far down as will touch the anterior edge of the first molars 

 of the shaded figures of our fossil species, it will be seen how far 

 behind this line the first molars of the living species represented 

 in outline are. If the whole length of the dental series fi-om hind 

 edge of last molar alveolus to front edge of incisor be taken as 

 unity, the ratio to it of the molar series in the P. jjliocenus is 

 yVV) l>ut only ^W in the most nearly allied recent species, the 



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