444 



individual. These ridges become less salient in the course of the oblique wear of the 

 crown of the premolar from the outer to the inner ridge, as in fig. 6, Plate LXXXVIII.; 

 and in old individuals they are ' polished off,' as in fig. 10, Plate CIX. But all the 

 generic and specific characters of the premolar of Sthenurus Brehus from Mitchell's 

 Breccia-cave in New South Wales are repeated in the present specimens from the 

 fluviatile beds of Queensland. The same may be said of all the succeeding molars which 

 in the type-specimen are sufficiently complete for comparison. The last molar in the 

 present example (Plate CIX. fig. 3, m 3) has not quite come to the grinding level, and 

 its ridges are untouched. The enamel-fold from the inner angle of the hind ridge, which 

 defines by its oblique tract along the hind surface the angular depression th,ere, seems 

 as if it were folded on itself or notched at its basal termination. 



The zygomatic process (Plate CVIII. fig. 1, 21') is more perfectly preserved than in 

 any other fossil, transmitted, of the genus Sthenurus ; it descends below the level of the 

 grinding-surface of ma; in older examples it would show the same relation to m 3, as 

 the grinders move (or seem to move) forward. 



I next proceed to notice the portions of skull of a more aged individual of Sthenurus 

 Brehus, from Clifton, Queensland. The laterally crushed maxillary part of the skull 

 (Plate CIX. fig. 4) includes the entire molar series of the left side, and major part of 

 that of the right side. The premolar (p 3) with a fore-and-aft length of 10 lines (20 

 millims.) in the type-specimen (Plate LXXXVII. fig. 7,^3) is but half a millimetre 

 less in the present fluviatile fossil, and this seems due to the wear of the anterior pro- 

 minence ; but all the formal characters are closely repeated. 



I have had no evidence from the spelaean haunt of the Thylacoleons, of a Sthen. Brehus 

 which had attained the experienced age of the yielder of the present Queensland fossil. 

 The molar contiguous to p 3 contrasts, as usual, its great degree of wear with the fresher 

 crown and higher level of the antecedent subsectorial tooth ; the fore-and-aft diameter, 

 6 lines (12 millims.), is the same in both fossils ; the minor transverse breadth in the 

 Queensland specimen is due to the wearing down of the outer angles of the transverse 

 lobes or ridges, which are prominent in the cave-fossil. The superiority of size, slight 

 as it is, in m \ of the type-subject of Plate LXXXVII. figs. 5 & 6, is chiefly due to the 

 minor wear of the crown of that tooth in the cave-fossil. The last two molars occupy a 

 longitudinal extent of 1 inch 6 lines (37 millims.) in both specimens. The linkless pre- 

 basal ridge (/') is transverse, not curving at either end to be continuous with the corre- 

 sponding angles of the fore lobe ; the low short mid link (r) is less distinctly continued 

 to the inner angle of the fore lobe than in Sthenurus Atlas ; the depression on the hind 

 surface due chiefly to the ridge (t) curving from the inner and hinder angle of the hind 

 lobe toward the outer side of the base of the crown, with the lower and shorter ridge (g) 

 from the outer angle, are all characters of Sthenurus Brehus, repeated in the present as 

 in the preceding Queensland sedimentary fossil. 



The left molar series in this instructive specimen (Plate CIX. fig. 4) occupies a lon- 

 gitudinal extent of 3 inches 3 lines. 



