467 



Sthermri, Protemnodons, and Procoptodons, which, in their shorter and deeper diastemal 

 and symphysial part of the mandible, exemplify the transition to Nototherium. 



The extent of the premaxillaries (22) from the alveolar outlets to the anterior bony 

 nostril (n) is relatively greater than in any skull of a living Kangaroo I have yet seen 

 (compare fig. 2 with fig. 3, Plate XCVL). The tract in question slopes backward as it 

 rises and curves, more vertically near the nostril, where it swells into a pair of low 

 tuberosities (ib. fig. 1, n). So far the union of the two premaxillaries is close, seem- 

 ingly anchylosed, though the mid line of their symphysis is traceable. In this character 

 Patorchcstes offers a resemblance to the Koala and Wombat*. A little behind the 

 tuberosities each premaxillary sends upward its plate to form the outer walls of the 

 nostril. The fore or free edge of this plate is thick, rounded, and slopes backward as it 

 rises in a greater degree than the subnasal coalesced plate. 



Of the right side-plate but an inch and a half is preserved ; the left one (ib. ib. 22 ) 

 is continued to its junction with the maxillary (21') ; and this extends backward to near 

 the orbit, 7-| inches from the incisive alveoli. The upper border of this plate is, at first, 

 thinner than the anterior or ascending border, but gains in thickness as it approaches 

 the orbit (Plate CV. fig. 1, 21'); it may have been broken and the fractured margin 

 worn smooth and obtuse; as it is, it shows no trace of the junction with the nasal bone. 

 As much of the plate as remains is nearly vertical, neither swelling outward, as in Macro- 

 pus major and Osphranter, nor bending inward at its upper part to join the nasal, as in all 

 recent Kangaroos. The external nostril must have been relatively narrower, and seems 

 to have been longer and more upward in aspect than in other known Macropodidai. 



The floor of the nostril is continued backward by the coalesced premaxillaries 2 inches 

 behind the lower border of the aperture (Plate CV. fig. 1, n); it is here half an 

 inch in breadth, concave and pitted along the line of the interpremaxillary suture. 

 Then, seemingly, it has been broken off, the thinner vertical plates rising from the par- 

 tition of the confluent prepalatine openings (ib. a), which are seen at a lower level. 

 Behind these the bony base of the " septum narium " rises for about half an inch before 

 its fracture ; and it can be traced back three inches (as at 11) before it suddenly sinks 

 down to the lower level of the upper surface of the bony palate (ib. b b). This sub- 

 sidence is more abrupt than in living Kangaroos (ib. fig. 2, b b), and each lateral division 

 of the superpalatal part of the floor of the nasal chamber forms, anteriorly, in Palor- 

 chestes a blind fossa (ib. fig. 1, b b) below the level of the floor of the antorbital part 

 (ib. n') of that chamber. 



Some traces are discernible of the suture between the premaxillary and maxillary 

 upon the palate (Plate XCVII. fig. 1, 21') and upon the side of the facial part of the 

 skull. Behind the third incisive alveolus, on the right side, a narrow oblique cavity like 

 an alveolus (Plate XCVL fig. l,c) is exposed by fracture or attrition of the outer palate 

 of the premaxillary, into the base of which cavity opens a small vascular or nervo- 

 vascular canal ; this may have contained the germ or aborted rudiment of a canine. 



* Plate XXXVI. figs. 3 & 4. 



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