BY C. W. DE VIS. 103 



Lower premolar elongate, bicuspidate, without intero-posterior 

 cusp. Molars smooth or with accessory plates, without posterior 

 groove or basal talon. Lower contour line of mandible a gentle 

 curve throughout. 



Dimensions. 



Maiidibular. — The full series of true molars is 39-0 in length 

 when aged \\); the tirst four cheek-teeth measure 38*0 (1); the 

 first three 28*6 (1); the last three 30*5 (1); the last two 22-5 and 

 23-5 (2). The premolar 7-5 and S'O (2). The width of m.^ is 

 from 7'7 to 8-4 (6). The anterior depth is from 20-2 to 23-5 (4); 

 the posterior from 18-4 to 22*0 (5); the thickness from 10-1 (aged) 

 to 14-1 (5). The external length is 92-0; the internal 72'0. 



Thoucjh the thickness of the mandible has the same ran^e as in 

 H. agiJis, which of modern wallabies has the stoutest underjaw, 

 its length and depth are comparable with those of the kangaroos 

 only. This is also the case with the length of the cheek-teeth, 

 which may be estimated at 50 '0 in young adults, and with the 

 width of the molars, but from the kangaroos it is at once 

 distinguished by the structure both of premolar and molars. 



Mandibular.— V.^ (PL xvii. fig. 1) elongate, narrow, diameters 

 8*0 X 3 4, bicuspid; crest a little to the inner side, deeply notched 

 at its anterior two-fifths. Anterior cusp a well defined strongly 

 compressed cone separated from the longer posterior part of the 

 lobe by a deep gooove descending upon each side of the crown 

 nearly to the base and by the notch in the crest; a slight incras- 

 sation of the crown over the intero-posterior angle does not affect 

 the general parallelism of the sides. Equal in length to m.^. 



Molars. — (PL xvii. fig. 2). These show a tendency to develop a 

 single erect compressed process at the bottom of the inner mid 

 valley— I.e., a rudiment of an accessory link similar to that in the 

 upper teeth of Palorchestes and M. pan (infra.). This process 

 occurs in two examples. 



