2G-1 



gradually shallowing to the fore end. Posteriorly the channel rapidly widens to the 

 intermolar space, then gradually expands, preserving or gaining depth to the hind border 

 of the symphysis (s). The entire length of this confluent tract of the mandibular rami 

 is 5 inches 10 lines; the thick rounded hind border is on the vertical parallel with the 

 hind lobe of the third molar (m 1). It is satisfactory to find this character of the former 

 mandible of Nototherium Mitchelli (Plate XXXVIII. fig. 2, s) here repeated. The 

 under part of the hind end of the symphysis shows the insertional depressed surface 

 (Plate XXXIX. fig. 2, v, v, of similar size and shape to that in the subject of Plate 

 XXXVIII. fig. 3, v). The symphysis is subcompressed anterior to the molars, but the 

 transverse diameter diminishes less gradually than the vertical one. 



The present mandible is of a full-grown and, from the wear of the teeth, rather aged 

 individual. The last three molars and a portion of the second are in place in the right 

 ramus : the first, second, and part of the third molars remain in so much as is preserved 

 of the left ramus. 



The fore-and-aft extent of the molar alveoli is G inches 10 lines; that of the three 

 hindmost is 5 inches 2 lines. I give this measurement, as well as the first, to show the 

 close correspondence in size of the present with the preceding mandible of Nototherium : 

 the present specimen is rather smaller ; the bone is rather more slender ; the vertical 

 diameter, for example, of the ramus anterior to the foremost molar-socket is 2 inches 

 4 lines, in the subject of Plate XXXVIII. it is 3 inches ; the vertical diameter behind 

 the socket of the last molar in the subject of Plate XXXIX. is 2 inches 10 lines, in 

 that of Plate XXXVIII. it is 3 inches 9 lines, in the type jawf it is 3 inches 8 lines. 

 With the closer conformity in the molar series, I infer the more slender proportions 

 of the present mandible to be sexual, and to indicate its having come from a female 

 Noto there. 



Rather more of the base of the coronoid process (Plate XXXIX. figs. 1 & 3, g, o) 

 is here preserved than in the subject of Plate XXXVIII. ; it occupies the same pro- 

 portion, and shows the same shape and curve as in that jaw ; the dental canal perforates 

 its hind part in the same position and with the same obliquity. The postalveolar pro- 

 cess, broken as in the former mandible, and as it usually is in these Australian fluviatile 

 fossils, holds the same relative position to the last molar tooth as in the male jaw. The 

 smooth oblique channel between the fore part of the coronoid and the last alveolus has 

 a breadth of 9 lines in the female, instead of 12 lines as in the male specimen. The 

 anterior inflected angular border repeats the characters of the part in that specimen, but 

 is not entire ; the exceptionally perfect condition of the part in the type mandible % 

 gives consequently valuable evidence of this character. 



The commencement, an inch above the anterior angular inflection, of the posterior 

 inflected margin (Plate XXXIX. figs. 1 & 5, a) and the corresponding outswelling 

 at the outer part of the ascending ramus (ib. fig. 5, h) indicate more definitely than 

 in the first described mandible the part from which the neck of the condyloid process 



t Loc. tit. ; and Cut, fig. 1 + Lot. tit.; and Cut, fig. 1, d. 



