420 



distortion which this cave cranial fragment has undergone indicates a persevering exercise 

 and diverse direction of force, such as only accords with the operations of the powerful 

 jaws of a large carnivore. 



A third example of Sthenurus Brehus (Plate LXXXVIII. figs. 5, 0, 7) has readied 

 me, through the persevering and successful cooperation of Dr. Bennett, F.L.S., which 

 more closely or directly shows the distinction of this species from Sthenurus Atlas 

 ( Plate LXXX1V. figs. 4, 5, ; Plate LXXXVIII. figs. 1-4), as it consists of an almost 

 identical portion of the upper jaw and grinding series of teeth with that which yielded 

 those instructive characters of the smaller giant Wallabee. 



The longitudinal extent of the dental series in the present maxillary fossil is 3 inches 

 5 lines; in Sthenurus Atlas it is 2 inches 10 lines. The dimensions of the premolar 

 are precisely those of the cave-specimens (Plate LXXXVII. figs. 7, 8, 9). The 

 characters which mark the species are closely repeated. The fore part of the inner 

 lower wall (b) is more distinctly marked off from the oblique ridge (f) in a small 

 notched prominence (f). The hollow between the walls a and b is rather deeper, and 

 there is one low transverse ridge at the bottom of the hollow. The hind triangular 

 depression (c) and other generic characters of the premolar of Sthenurus are instructively 

 repeated. The same may be said of the succeeding bilophodont molars ; the degree of 

 wear of which is identical with that of the type maxillary specimen of Sthenurus Atlas 

 (Plate LXXXIV. fig. 0). The inner end of the prebasal ridge (Plate LXXXVIII. 

 fig. 5,f) extends further forward from the front lobe, a. 



The masseteric process (ib. fig. 5, 21') seems to have been relatively longer, and more 

 compressed from before backward than in Sthenurus Atlas (Plate LXXXIV. fig. 4, 21') ; 

 it holds the same relative position to the last two molars. The outlet of the suborbital 

 canal is 1 inch lines in advance of the orbit, and 9 lines above the base of the pre- 

 molar, on a vertical parallel with the hinder third of that tooth. 



The depression at the back of m 3 (Plate LXXXVIII. fig. 9) is bounded by two 

 ridges which converge from the outer and inner apices of the hind lobe as they approach 

 the base of the crown. The inner ridge (ib. fig. 10, g) is the strongest and longest ; it 

 curves toward the base of the outer part of the hind lobe, but subsides before attaining 

 either the base or the outer border ; its termination is marked off by a short notch. 

 The outer posterior ridge subsides before reaching the basal end of the inner one. Both 

 ridges are due to an excavation of the hind surface of the hind lobe, repeating more 

 strongly the depressions on the same surface of the front lobe ; and the inner hind ridge 

 of the hind lobe is the serial repetition of the ridge which runs from the corresponding 

 apex of the front lobe to the low mid-link. The hindmost molar has been lost, but the 

 alveolus remains (ib. fig. 6, m s), showing that the transverse pair of anterior roots had 

 been developed, and the longitudinally impressed, but incompletely divided, hind root, 

 had been formed ; the crown had evidently been in place, though from the slight abrasion 

 of the apical ridges of the lobes of m 2, in m 3 they may not have been worn. 



A second specimen of a smaller portion of the right maxilla, with the three hinder 



