io2 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. XIV. 



between the nasals, frontals and maxillary. They do not exclude the 

 maxillaries from contact with the frontals, however, and despite their 

 great length their posterior endings are in advance of the orbits. 



Premaxillae. The premaxillae are longer than high and reach quite 

 to the bases of the canines. The maxillary suture approaches the per- 

 pendicular as in Perameles and most diprotodonts. A narrow posterior 

 ascending branch extends backward between the nasals and the maxil- 

 lary to the plane of the front of the middle premolar. The palatine 

 processes of the premaxillae do not extend the full length of the anterior 

 palatine vacuities as in most other marsupials, but meet similar processes 

 of the maxillary which extend forward. The bony division of the 

 anterior vacuities thus consists of premaxillary elements only in its 

 anterior three-fifths. The only other marsupials in which I have found 

 this arrangement are the peramelids; in all others the premaxillary 

 processes extend nearly or quite to the posterior boundary of the 

 vacuities. In every respect, therefore, the premaxillae are more similar 

 to those of the peramelids than of any other marsupial. 



Maxillae. The slender processes of the maxillaries projecting 

 forward in the anterior palatine vacuities are only paralleled among the 

 peramelids. The posterior fenestration of the palatal aspect of the 

 maxillae also resembles closely that of Perameles. In their upward 

 extension, the maxillae are not greatly narrowed between the antorbital 

 vacuities and the lacrymals, but meet the frontals broadly at a point 

 about even with the front of the orbits and somewhat caudad of the 

 posterior nasal endings. In these respects they are conspicuously 

 different from those of the didelphids. 



In uniting with the jugals, the maxillaries send out a slender prong 

 which takes a larger part in the formation of the anterior root of the 

 zygoma than is usual in marsupials and contrasts especially with the con- 

 dition in most polyprotodonts in which the jugal is expanded on the 

 face below the lacrymals. In general, however, the relation of the an- 

 terior root of the zygoma to the maxillary is as in polyprotodonts, that 

 is, the principal part of the maxilla, including all the molars except the 

 last two, is anterior to the zygoma. This is in decided contrast to the 

 diprotodonts in which that part of the maxillary bearing the molars is 

 largely posterior to the anterior root of the zygoma. In some forms, 

 especially among the Phalangeridae, the root of the zygoma rises from a 

 point as far forward as the last premolar and consequently the entire 

 molar series is posterior to it. In polyprotodonts, on the contrary, it is 

 rare for more than the last reduced molar to lie posterior to the zygoma. 

 This constitutes one of the most striking resemblances to polyprotodonts 

 shown by the skull of Canolestes. 



