126 FOSSIL JAWS OF MACROPODIDJ^^, 



by a raised tubercular basal riin enclosing a concave ledge. Outer 

 surface of crown impressed at anterior third, the impression 

 defining the outer edge of an anterior cusp 6; on the posterior 

 half of the impression are two very distinct vertical ribs. In a 

 maxilla which seems to belong to this species the premolar (PL 

 XVIII. fig, 8) is elongate obovate, with diameters 12-3 and 5*7 and 

 a little contracted at the anterior third. The intero-posterior 

 tubercle is more entirely separated from the lobe; and the whole 

 tooth has a facies different from that of the preceding tooth, which 

 may be taken as the type of the species. Yet as m. ^ in this 

 maxilla has relics of the sepiment in its outer midvalley, and as 

 the variation in the premolar may be paralleled among recent 

 species, there is not at present sufficient ground for referring it to 

 a separate species. 



Molars (PL xviii. fig. 10). — The posterior molars differ in no 

 respect from those of M. iniayister save in somewhat superior size; 

 m.- most frequently shows a vertical fold descending from the 

 middle of the hinder surface of the fore lobe external to the mid- 

 link, and meeting its fellow of the opposite side at the bottom of 

 the valley h\ or as in the type specimen forming there an erect 

 plate. In m. ^ this fold forms a more complete sepiment a from 

 lobe to lobe; it is constant in occurrence, and traces of it are 

 visible as long as the lobes persist. It is not a little remarkal:)le 

 that this one of the structural characters of Palorchestes should 

 reappear in a species of Macropus. 



Mandihular. — P.* (PL xviii. fig. 7) ovate, with the sides mesially 

 contracted, and with diameters S'O and 4-0. Crest mesial; a very 

 small intero-posterior cusp separated from the lobe apically and 

 posteriorly; inner side of crown somewhat concave in front of the 

 cusp, outer rather concave with one or two obscure ribs about the 

 middle. The cusp disappears under wear. A series of four young 

 teeth extracted from their crypts at an early stage of growth or 

 exposed from above show^s that the tooth in its growth undergoes 

 considerable change of form. At the earliest phase observed it 

 resembles in shape the end of a cold chisel with a dent on each 



