414 



incompleted eruption of the molar (m 1) and the still hidden and undeveloped state of 

 m •_> and m .< ; whence may be inferred a like precocious appearance of the premolar in 

 the working series, with the concomitant shedding of the two anterior deciduous teeth 

 (d d j), the premolar preceding the penultimate molar in entering upon the work of 

 mastication. The differences observable between the fossil and the recent Kangaroos 

 combining the above characteristics of the proposed subgenus are, at least, specific. 



The premolar, divided in both by a vertical cleft into a smaller anterior and a larger 

 posterior lobe, shows in the fossil a more definite basal ridge along the outer side of the 

 latter lobe than in Phascolagus erubescens ; there is also a more definite outswelling of 

 the hind part of the hind lobe in Phascolagus alius ; two feeble grooves divide the 

 outer surface of the fore part of the anterior lobe into three vertical prominences, but 

 these are faintly marked in the present fossil. 



In the bilophodont molars the prebasal ridge is narrow and the indication of the fore 

 link is minute. The mid link is narrow, neatly defined, and sinks rapidly from the 

 inner and posterior apex of the front lobe to the lower part of the interlobal valley. 

 The postbasal ridge is represented by a similar outbending and descent of a sharp 

 ridge from the inner angle of the hind lobe ; which ridge, curving to subside upon the 

 outer part of the base of the hind lobe, circumscribes, below, the depression or trans- 

 verse concavity on the hind surface of that lobe. 



The position and extent of the origin of the anterior pier of the zygoma is the same 

 in the fossil and the recent species compared. The configuration of the hind margin 

 of the bony palate is the same. But our extinct Kangaroo shows these characters of 

 its subgenus on a larger scale than the largest known existing species of Phascolagus. 

 The tooth d * (Plate LXXXII. fig. 2) is as large as its homologue in Macropus major ; the 

 antero-posterior extent of m 1 is a trifle more in the fossil. We may infer from the 

 superior size, both absolute and relative, of the premolar in Phascolagus alius that the 

 permanent molar dentition would be represented for a longer period of life by the five 

 teeth, p 3, d i, m i, m 2, and m 3, than in the existing Great Kangaroo (Macropus 

 major). 



The specimen above described, with the rest of Sir Thomas L. Mitchell's first 

 collection of cave-fossils from Wellington Valley, is in the Museum of the Geological 

 Society of London. I am indebted to the President and Council for the opportunity of 

 giving new and better figures of the type of Phascolagus alius than the original ones in 

 the ' Appendix ' of the above-cited work. 



In the 1 collection of fossils from the freshwater deposits of Queensland, lately 

 received from Dr. George Bexxett, F.L.S., of Sydney, New South Wales, there are 

 instructive evidences of Phascolagus alius adding to our knowledge of its cranial and 

 dental characters. The specimen No. 38752, Register of Fossils, British Museum, is 

 part of a right maxillary of a young animal with the dentition in nearly the same state as 

 he subject of figs. 1 & 2, Plate LXXXII. The germ of the premolar seems rather less 

 than in that type specimen ; but the hind angle was broken off in the work of exposure, 



