90 FOSSIL JAWS OF MACROPODIDJ^:, 



of them being the outer one on the intero-anterior face of the hind 

 lob? in the lower and intero-posterior face of the fore lobe of the 

 upper teeth. Hinder surface of molars with strong ascending- 

 folds, one or two on the lower, two or three on the upper (PI. XV. 

 figs. 8-9). Upper premolar short with a broad ledge, not extend- 

 ing beyond the posterior three-fifths of its inner side; its cavity- 

 traversed by a longitudinal sinuous ridge. Lower premolar sub- 

 triangular with a group of sinuous folds within the posterior cleft. 



Dimensions. 



Mandible. — The entire series of cheek-teeth varies from 82-5 to 

 93-7 (6); p.*, m.\ m.^, m.^ measure 68-0 (1); m.^, m.^, m.'^ 53-0 

 (2); m.i, m.2 34-2 (1); m.^, m.^, m.^ from 58-1 to 65-5 (2); m.* 22-2 

 (1); mp.* 13-4 (1). The premolar is from 12-5 to 14-5 (5). The 

 width of m.^ ranges from 15-0 to 19-8 (10); its length being from 

 18-4 to 21-5 (10). The anterior depth of the mandible is from 

 50-0 to 60-0 (7); the posterior depth from 37*0 to 52-5 (6); the 

 thickness from 34*7 to 42*5 (7). The entire length fore and aft 

 is 147-5 (1). 



Maxilla. — The molars m. -, m. *^,m.'^ measure together 51 -5 (1); 

 m.-^ m.3 from 38-5 to 42-1 (2); p.^ mp.*, m^, m.^ 46-6 (1). , An 

 immature premolar has diameters 12-0 x 9-4; the milk premolar 

 is 9-2 in length. 



With one exception all these dimensions come well within the 

 allowable limits of range in a species. The width of the teeth 

 differs to an extent which is nearly a third of its minimum; this 

 is sensibly greater than in the three living species which show the 

 greatest latitude in this respect — M. gig aniens, H. agilis, and H. 

 ruficollis — but the difference is too small to stand as a lone 

 objection to the fusion of S. rapha with S. goliah. 



Form of teeth. 



Mandibular. — P.* (PI. xv. fig. 7.) Generally triangular, with 

 rounded sides and angles, rarely an irregular suboval. Outer 

 surface of crown impressed at its anterior two-fifths or thereabouts, 



