433 



Thomson and Mr. Krefft in the Breccia-cave of Wellington Valley, and deposited in 

 the Museum of the Natural-History Society of Sydney, New South Wales. 



The photographs, liberally transmitted to me by the Trustees of that Museum, and 

 prepared under the superintendence of their able Curator, Mr. Krefft^ give an outer 

 side view (Plate LXXXVII. fig. 1), an inner side view of part of the left premaxillary 

 and teeth (ib. fig. 2), an inner side view of the premolar (ib. fig. 3), and a view of the 

 grinding-surface of the two best-preserved molars (d i, m i, left side, ib. fig. 4). These 

 teeth, the premolar of the left side, and perhaps the front and second incisor are 

 tolerably perfect; the remaining teeth have suffered more or less fracture; but the 

 remains of the molar series in situ on the left side enable the requisite admeasure- 

 ments and comparisons as to size to be made with the mandibular teeth of the kinds of 

 Protemnodon previously described. From their close accordance in this character with 

 the mandibular teeth of Protemnodon Mimas (Plate LXXXVI. figs. 1-3) I refer the 

 subject of the photographs to that species. 



The upper incisors, as in existing Macropodidce, are three in number in each pre- 

 maxillary. The foremost (Plate LXXXVII. fig. 1, i \) is curved lengthwise, with the con- 

 vexity forward, and has a thick enamelled crown, with the fore part convex transversely ; 

 its convex cutting-edge projects slightly beyond that of the second incisor. The crown 

 of this tooth (i 2) is smaller, less convex, and less prominent than that of the foremost one. 

 The indications of the socket of the third incisor support the inference that, as in the 

 large existing Kangaroos (Macropus major, Macropus (Osphranter) robustus, Macropus 

 {Osphranter) ruf us), the antero-posterior dimension of the crown of that tooth exceeded 

 that of the second and first incisors ; but of the precise proportions of these teeth 

 exemplifying specimens are still desiderata. 



The antero-posterior extent of the incisive alveoli of the left premaxillary is 1 inch 

 5 lines, that of the toothless interval between the third incisor and the premolar is 

 1 inch 9 lines ; the extent of the molar series is 3 inches 2 lines. The diastema is rela- 

 tively shorter than in the above-cited existing Kangaroos, and indicates a corresponding 

 condition of the lower jaw, whereby, as regards length. Protemnodon resembles 

 Sthenurus. 



The premolar (p 3), however, retains in the upper jaw the more simple trenchant form 

 which afforded the subgeneric distinction in the homotypal tooth below. There is a 

 slight expansion of the fore and hind parts of the crown, the intermediate part of the 

 blade having an entire and nearly straight trenchant edge, with the indication of a low 

 ridge or cingulum along the base. The corresponding part on the inner side of the 

 crown (ib. fig. 3), though much less developed than in the upper premolar of Sthenurus, 

 adds another character differentiating Protemnodon Mimas from Protemnodon AnaJc. 



The bilophodont molars have both pre- and post-basal ridges ; the former, as usual in 

 upper molars, less produced than in the lower molars. The indication of the fore link 

 is recognizable, and that between the main lobes is more plainly shown (ib. fig. 4) ; 

 the mid link is worn down to the base, exposing a broader tract of dentine in the 



