283 



on this ground. In both examples they come near, in size, to the anterior molar (d 3) in 

 the upper jaw of Nototherium Mitchelli. 



The socket of the second molar (Plate XLIV. figs. 1 & 2, d 4) has a fore-and-aft extent 

 of 1 inch 1 line, which accords closely with that in Plate XL. figs. 1-5, d 4). 



The third molar (Plate XLIV. figs. 1 & 2, m 1) shows both lobes abraded to their base ; 

 the enamel still crosses the valley, but that between the hind basal ridge and the hind 

 lobe is worn away and a broad smooth expanse of dentine and osteodentine is exposed, 

 11 lines by 6 lines in diameter. The fore-and-aft extent of the remaining basis of the 

 crown is 1 inch 6 lines ; the breadth of the hind lobe is 1 inch. These dimensions 

 accord sufficiently closely for specific identity with those of to 1, in the immature subject 

 of Plate XL. 



In m 2 (Plate XLIV. figs. 1 & 2) the enamel of the hind lobe is worn down to the level 

 of the hind basal ridge, which is partly abraded, but not down to the dentine. The 

 narrower and lower anterior basal ridge is intact, and the enamelled crest of the anterior 

 lobe rises 3 lines above it. The anterior productions (r, r) of the two lobes, rudi- 

 mentally indicating the linking bars in certain Kangaroos, are instructively marked at 

 the present stage of attrition. The posterior basal ridge of this tooth overlaps the ante- 

 rior one of the next (to 3), the front lobe of which rises 5 lines above that level. The 

 anterior prominence near the outer end of each lobe repeats the short forward angle in 

 the contour of the enamel as here worn down. The corresponding prominence of the 

 hinder lobe (r) inclines toward the middle of the valley ; the macropodal affinity, slight 

 as it is, is more strongly marked in Nototherium than in Dijorotodon*. 



The fore-and-aft extent of to 3 is 1 inch 10 lines, exceeding by 2 lines that of the 

 opposing molar above (Plate XLIII. fig. 4, m 3) : in this, also, a macropodal character is 

 repeated. The transverse extent of the front lobe of to 3, fig. 3, is 1 inch 4 lines; that 

 of the hind lobe is less. 



The entire extent of the lower molar series is 7 inches 2 lines, about 2 lines less than 

 that of the upper molar series in the skull of Nototherium Mitchelli (Plate XXXVI. 

 fig. 1). 



In the series of sockets of the lower jaw of possibly the same individual, the partition 

 between the fore and hind fangs of each tooth is much thicker than that between the 

 sockets of distinct teeth. The transverse space between the hind lobes of the right and 

 left last lower molars is 2 inches 9 lines ; between the front lobes of the first molars 

 1 inch 5 lines. Each mandibular series describes a very slight curve as it advances 

 forward, with the convexity outward. The base of the socket of the incisor, which does 

 not extend beyond that of the first molar, is 1 inch 2 lines in vertical diameter, 8 lines 

 in transverse diameter. 



In the specimen of the mandible with the symphysis entire, or nearly so (known to 

 me by the cast, Plate XXXIX.), the molars show almost the same stage of attrition as 

 in the preceding specimen. The first and second molars are retained on the left side. 

 * Compare figures 11 & 18, Plate XXIV. with figures 1, 2, & 3 in Plate XLIII. 



24* 



