318 



PEOFESSOE OWEN ON THE FOSSIL MAMMALS OF AUSTRALIA. 



This portion (Plate XI. fig. 3 ; Plate XIII. figs. 4 and 5) fortunately includes the 

 camassial and tubercular teeth, and by the correspondence of these in shape and size 

 with the answerable teeth {p 4, m i) in the upper jaw of Thylacoleo (Plates XI. and XIV. 

 fig. 1), I believe it to belong to the same species. 



The lower carnassial tooth consists only of the ' blade,' which is thickest anteriorly, 

 with an even trenchant edge, describing a slight concavity lengthwise, and obliquely 

 abraded by the play of the upper tooth upon the outer side of the edge. The outside 

 of the tooth (Plate XI. fig. 3, p i) is convex lengthwise, and also vertically at the fore- 

 part: the inside (Plate XIII. fig. 4,j9 4) is concave lengthwise, except near the fore-part; 

 vertically it is convex at the base and concave above, the base being slightly grooved 

 vertically. The anterior margin of the tooth, which is the highest, is bounded by a 

 vertical ridge. The length of the crown is 1 inch 8 lines ; the height at its fore-part 

 is 9 lines; the thickness at the same part is 6 lines: the height and thickness of the 

 crown diminish toward the back part. The small tubercular tooth (Plate XI. fig. 3 ; 

 Plate XIII. figs. 4 and 5, m 1) is immediately behind the preceding : it consists, more 

 distinctly than the one above, of an anterior principal lobe and a small posterior one ; 

 the anterior lobe is convex on both sides, subcorneal, wdth a worn obtuse summit. The 

 antero-posterior extent of the crown is 7 lines ; the same extent of both the teeth just 

 equals that of the upper sectorial, and the lower tubercular is so situated as to play, in 

 lateral movements of the jaw, upon the upper tubercular. Behind the tubercular in place 

 there is the socket of a rudimental one, which cannot have exceeded 3 lines in its longest 

 diameter (ib. m 2). From this socket the coronoid process begins to rise, sloping upward 

 and backward. It is broken ofi" within half an inch of its origin. The fore-part of the 

 fossa for the implantation of the temporal muscle is preserved, showing by its depth the 

 strength of that muscle ; the anterior boundary of the fossa is vertical and convex 

 forwards. The ramus of the jaw preserves the same depth from the last socket to the 

 fore-part of that of the sectorial tooth. The symphysis (Plate XIII. fig. 4, s) begins 

 behind, at a vertical line dropped from a little in advance of the middle of the sectorial, 

 p * ; it is of a wide oval form. To judge from the cast, but little of the jaw appears 

 to have been broken away from the fore-part of the symphysis. The upper and fore- 

 part shows the alveolus and base of a tooth (Plate XI. fig. 3, c) which has projected 

 obliquely upward and forward. It is separated by an interspace of 3 lines from the 

 sectorial, and would seem to be the sole tooth in advance of it. If the ramus be really 

 jn-oduced at the upper part of the symphysis further than is indicated by the present 

 cast, it may have contained one or more incisors, and the broken tooth in question may 

 be the lower canine. If, however, this be really the foremost tooth of the jaw, it would 

 appear to be one of a pair of large incisors, according to the marsupial type exhibited 

 by the Macropodidw and Phalangistidoe. However this may ultimately prove to be, the 

 molar series in each ramus of the lower jaw is reduced to the enormous sectorial and 

 th(! two small tuberculars ; and it would seem, therefore, in the upper jaw, to be reduced 

 to the single sectorial and single tubercular on each side. It is possible that a canine 



