430 



fore and mid links are well shown in m s, and contrast with the better developed ones in 

 the somewhat larger Protemnodon represented by the subject of figs. 11, 12, & 13, 

 Plate LXXXV. 



The last molar in Protemnodon Anak rises, in the outer side view of the mandible, 

 clear of the front root of the coronoid process (ib. fig. 7, q). The fore part of the outer 

 crotaphyte excavation (fig. 7,f) sinks as abruptly from the prominent anterior border as 

 in Macropus and Halmaturus', but the cavity appears to be divided in Protemnodon by 

 a curved ridge into an upper ( /') and lower (a) channel, the latter being that which 

 leads to the large hinder orifice of the dental canal. A similar fracture of the ascending 

 ramus of the mandible in existing Kangaroos would not produce this appearance, but it 

 may be due to the minor development and closer approximation to the coronoid plate 

 of the base of the inflected mandibular angle in Protemnodon. 



In the depth or vertical breadth of the ramus beneath the last molar and the minor 

 degree of vertical convexity of that part, Protemnodon contrasts with the narrower and 

 more bulging character of the same part of the jaw in Macropus. It is rather less 

 convex, though narrower, in Halmaturus. There is a trace at a, fig. 8, of the beginning 

 of the excavation, or lower channel, leading to the intercommunicating aperture and to 

 the entry of the dental canal ; but the extent of the inner plate of the mandible, from 

 t to a, is not matched by any existing Kangaroo the lower jaw of which I have compared 

 with the fossil. 



In the extent of the edentulous and symphysial part of the mandible (ib. fig. 8, I, si) 

 Protemnodon agrees with Halmaturus rather than with Macropus ; but the syndesmotic 

 surface extends nearer to the alveolar outlet of the incisor (i), although it does not 

 indicate so firm a union as in Sthenurus (Plate LXXX1I. fig. 6). It extends more in 

 the axis of the ramus than in Sthenurus. 



The breadth of the incisor and that of the surface (Plate LXXXV. fig. 10, i) which 

 was opposed to the upper incisors point significantly to a Nototherian tendency. 



The configuration of the crown of the unworn molars (ib. figs. 11-13, m 2, 7/13) 

 in a portion of a mandibular ramus of a large Protemnodon Anak supplements the 

 illustrations of the mandibular dentition of the species. The fossil was part of an 

 individual, probably male, in which the hindmost molar had recently risen " into place." 

 The links (fig. 13, r, s) are more neatly defined in this unworn tooth, which also had not 

 moved forward so clear of the coronoid process (fig. 11) as in the older example (fig. 7). 



§11. Protemnodon Og, Ow. — The subject of figs. 5 & 6, Plate LXXXV., with a certain 

 increase of size of both mandible and molar teeth, repeats the form and size of the pre- 

 molar (p s) in Protemnodon Anak, but shows a distinct linear indication of the post- 

 basal ridge g, and a more definite development of the links r and s in the last molar, m 3. 

 These characters may be subsequently found in other individuals, and sufficiently evince 

 an established variety ; but they are so strongly marked in the still larger mandibular 

 fossils next to be noticed as to justify their ascription to another (zoological) species, 

 and the imposition of the name which heads the present section. 



