404 



lobe of the hindmost tooth (m 3). In the foremost (d \) the channel of dentine along 

 the mid link is not quite exposed, the enamel at the base of the link still remaining. 

 The two anterior deciduous molars and the premolar have been shed and the alveoli 

 obliterated. This, therefore, is from a fully mature individual. The three teeth (d 4, m 1, 

 m a) homologous with the last three molars of the young specimen (ib. figs. 6-8) occupy 

 the same longitudinal extent, viz. 1 inch 8^ lines : with the fully developed succeeding 

 teeth they exemplify the later stage of the upper molar dentition in the present extinct 

 species. The last molar (ib. figs. 15 & 16, m 3) shows well the characteristic modifications 

 of its working-surface in Macropus Titan as compared with that in Sthenurus Atlas 

 (Plate LXXXIV. fig. 6, m 3): the prebasal ridge (f) is broader ; its margin rises (the tooth 

 being viewed prone) from the outer end to near the middle of its transverse course, then 

 sinks more rapidly to its inner end, which bends up upon the front lobe. From the 

 low or open angle thus described by the sharp margin of the prebasal ridge, the linking 

 process (s) extends to near the middle of the fore part of the front lobe. In Sthenurus 

 Atlas there is no front link ; the margin of the narrower and lower prebasal ridge forms 

 no angle as it sinks to terminate at the fore and inner end of the front lobe. 



The mid link (Plate LXXXI. fig. 15, m 3, r) comes off from the front lobe nearer to 

 its inner end in Macropus Titan, but not from that end as in Sthenurus Atlas (Plate 

 LXXXIV. fig. 6, m 3, r). It is more developed in Macropus Titan, and its course is more 

 longitudinal as it recedes to abut against the middle of the hind lobe ; the postbasal 

 ridge (g) extends from the postinternal angle of the hind lobe downward and outward 

 to the postexternal part of the base of that lobe, leaving a well-marked oblique dent 

 or cavity on the posterior surface of that lobe. In Sthenurus Atlas a general slight 

 concavity of the hind surface of the hind lobe of m 3, upper jaw, is bounded 

 below by a feeble postbasal ridge. With an equality of breadth, the fore-and-aft extent 

 of the last molar in Macropus Titan exceeds that of Sthenurus Atlas by 1 line. 



The hind border of the front or maxillary pier of the zygomatic arch is on the vertical 

 parallel of the interval between the fore and hind lobes of m 3 (Plate LXXXI. fig. 15). 

 The retrogression of this buttress of bone is concomitant with the grinding-function now 

 assumed by the last of the molar series (compare with figs. 10 & 8). 



The anterior outlet of the suborbital canal (ib. fig. 16, 21) is 1 inch in advance 

 of the anterior border of the orbit. Three lines behind the antorbital foramen is the 

 smaller oblique aperture (a) leading down to the interior of the maxillary bone. The 

 outer plate of the maxillary, in advance of and below the antorbital foramen, shows a 

 depression ; while the maxillary wall of the nasal cavity swells outward in existing Kan- 

 garoos. The proportion of the bony palate preserved shows the small narrow fissure 

 where the maxillo-palatine suture bends inward opposite the fore part of ms; elsewhere 

 the palate is entire, as in Macropus proper, in Boriogale, and Osphranter. The fore part 

 of the palate near d 4 shows a longitudinal channel (ib. fig. 15, b), 4 lines broad, bounded 

 anteriorly by a ridge, or hind part of the diastema, extending forward and inward from 

 the fore part of the socket of d 4, where the sockets (here obliterated) of p z and d 3 had 



