428 



lower molars, like the upper ones, retain the Macropodal bilophodont character. But 

 the lower premolar of Protem/nodon shows no indication of the three-lobed division 

 which is marked on the outer surface of the crown of that premolar of Dendrolagus. 

 It is rather more like that in the Potoroos, though the indications of vertical grooves 

 and ridges on the compressed part of the crown between the slight fore and hind 

 thickened ends are feebler. 



The greatest height of the crown of the premolar, which is at the fore part (Plate 

 LXXXV. figs. 3, 5, 7, & 8, p s), is but half the antero-posterior diameter; the utmost 

 thickness (at the back part of the crown) (ib. fig. 2) is less than the height. The free 

 or trenchant margin is straight, and runs nearly parallel with the base of the crown. 

 The fore border is subtrenchant, the hind one flattened, and closely adpressed against 

 the contiguous molar. The fore part is defined behind by the subsidence of the narrower 

 following part of the crown on the outer side (ib. fig. 3, p s), and, less definitely, 

 by the foremost of the shallow vertical grooves on the inner side (ib. fig. 8). The base 

 of the fore part of the crown bulges forward beyond the anterior root. The hind 

 part of the crown slightly expands, but is not defined, like the front expansion, from 

 the rest of the crown. A feeble indication of a " cingulum " runs along the outer side 

 of the base of the crown, and is more dubiously represented by a slight smooth out- 

 swelling along the base of the inner surface. The tooth is implanted by two antero- 

 posterior, slightly divergent, fangs. 



§10. Protemnodon Anak, Ow. — The subject of Plate LXXXV. figs. 1 & 2, the type 

 specimen on which the species Macropus [Protemnodon) Anak was founded*, is a 

 portion of a left mandibular ramus, including the molar series. All the teeth of the 

 permanent dentition are in place, and from the degrees of wear of their crowns it may 

 be inferred that the foremost (p 3) was the last to come " into line." 



Only the hinder angle of the enamelled trenchant border of the crown of this tooth 

 is touched, whilst the dentine is exposed on the ridges of the last molar (ib. fig. 2, m 3). 

 The crown of d 4 has been worn down nearly to the bases of the two lobes, and the 

 dentine of the mid-link connects the two exposed wide tracts of that tissue, forming the 

 bases of the worn-out ridges. The next molar (ib. ib. m 1) shows a greater degree of 

 wear ; the dentinal part of the mid-link is broader, and the lobes, as seen in the 

 side view (ib. fig. 1, m 1), are worn down lower or nearer to their base than in d 4. The 

 front lobe of m 2 has been abraded to the level of the link, which, being low in this 

 species of Protemnodon, is hardly touched. A broad tract of dentine is also exposed on 

 the hind lobe. A narrower bilobed tract appears on the front lobe of mu; the 

 enamelled summit of the hind lobe is smoothly worn downward and backward. 

 The prebasal ridge (f) is broadest in this tooth, and shows a low link (s) continued 

 from the fore part of the outer swelling of the front lobe. The inner alveolar border 

 (ib. fig. 8) runs from the postalveolar ridge (t) with a feeble concavity to m 1, and then 

 takes as feeble a convex course to the diastema (I). 



* Proceedings of the Geological Society of London, vol. xv. p. 185 (June 23, 1858). 



