10S 



of the specimen, which was deposited, with the rest of Mitchell's cave-fossils, in the 

 Museum of the Geological Society of London. 1 



I subsequently received the fragment of lower jaw (Plate VI. fig. 12), in which I 

 recognized the hoinologue of the problematical cave-fossil in situ, followed by a small 

 tubercular tooth and the debris of a second still smaller one, which seemed to terminate 

 the mandibular series of teeth. The specimen was from the bed of a tributary of the 

 Condamine. Here seemed to be, from this recent drift-deposit in Australia, the corre- 

 lative, on a gigantic scale, of the diminutive mesozoic British fossil, figured in Cut G, 

 ]>. 77. In Potoroos (Plate V. figs. 14, 15, and Cuts, figs. 13 & 14, p. 92) the molars 

 succeeding the sectorial tooth are many, are tubercular, and relatively larger than in 

 Thylacoleo and Plagiaulax. 



With the mandibular drift-fossil was associated the maxillary fragments (Plate VI. 

 figs. 9, 10) containing the sectorial molar, the left of which I inferred to have opposed 

 the lower homotype (fig. 12) ; for in that tooth the smooth surface due to attrition sloped 

 from above downward and outward ; in the upper sectorial the similar but more 

 extensive worn surface sloped from its edge upward and inward. It was plain that 

 these teeth had played upon each other like shear-blades. The resemblance to the 

 sectorial or ' carnassial ' teeth of the placental Carnivora was patent and strong. It 

 was further carried out by the presence of one small upper tubercular tooth (figs. 9 & 

 10, m 1) following the great sectorial blade— not set, however, directly behind it, but, as 

 in Felines (figs. 4, 7, 8), on the inner side of the hinder end, with the long axis of the 

 crown at right angles with that of the great sectorial. Here seemed to be an indication 

 of a placental exception to the grade of mammalian life characteristic of the indigenous 

 Australian quadrupeds. 



Of the right maxillary and sectorial, fig. 1, Plate VI. gives the outer side view, showing 

 the long and strong, deeply implanted anterior root, a, and the base of the more 

 longitudinally extended hinder root, b — the first supporting the fore part of the crown, 

 which is convex externally, the second the larger proportion of the crown, which is 

 longitudinally concave externally, alb this outer part of the crown being covered by a 

 plate of enamel. The outlet of the suborbital canal (c), and part of the suture between 

 the maxillary and malar (d) descending from the lower border of the orbit, are shown in 

 this fragment, and seemed to support the ' placental ' affinity. A similar view of a 

 corresponding part of the right maxilla of a llijana spelaa is given in fig. 2. In this 

 extinct placental Carnivore the outlet of the suborbital canal is shown at c, and the malo- 

 maxillary suture at d. In the sectorial tooth the anterior root (a) is long, thick, deeply 

 implanted, and descends from its apex to the crown of the tooth with a slight inclination 

 backward, as in fig. 1. The part of the crown which it supports is convex outwardly. 

 The division of the longer hinder part of the crown, supported by the broad lamelliform 

 root {b) } into three parts by the two vertical grooves {e,f) is more definitely marked; 

 1 4 Proceedings of the Geological Society of London ' for April 1831. 



