TERIOD IN QUEENSLAND, BY C. W. DE VIS 



113 



Pseudochirus (?) notabilis. — 



In a maxillary containing the premolar pin 4 witli three suc- 

 ceeding molars there is transmitted a well-kept record of another 

 type of Phalanger. The premolar is a distinctly bienspidate tooth, 

 consisting of an anterior subpyramidal and a posterior conical cusp, 

 united by a narrow mesial linking ridge ; a deep valley on either 

 side of the ridge is closed on the ectal side by a raised basal rim, on 

 the ental by a cingulum passing from the ental side of one cusp to 

 the other, divided by a notch nearly opposite the entrance of the 

 valley, and enclosing a dilated basal area on that side of the tooth. 

 The general form of this premolar is recognisable in that of Phalan- 

 gista, and in the atttitude of the two there is about the same 

 degree of obliquity ; but for a decidely near approach to the fossil 

 tooth the writer sought in vain among the Phalangers, until, 

 turning out the contents of a lady's reticule, brought from the 

 Fly River, New Guinea, he found a part of a skull of a young 

 Ouscus, with the deciduous premolar in place. With differential 

 details, this tooth is so similar to that of the fossil that both might 

 well be referred to the same genus, but inspection of the molars of 

 the fossil at once advises us of the danger of deducing such affinity 

 from a single tooth, in this instance at least. From Cuscus and 

 Phalangista alike they lead away — proximately to Pseudochirus 

 and Petaurista — ultimately to Phascolarctos. In these genera the 

 same leading characters are exhibited by the molar surfaces — in all 

 we note the ectal edge of the series, as supinated to view, much the 

 higher, its central line concave, each lobe traversed by concentric 

 folds of enamel — the outermost fold forming serially the edge of a 

 line of depressions on the summit or side of the ectal margin — the 

 innermost edging a lower line of hollows more or less distinct. In 

 Phascolarctos both rows of pits are so pronounced as to give a 

 peculiar facies to the teeth — the ectal row runs along the summit 

 of the cusps, the central folds are well nigh aborted. In Petaurista 

 the outer fold being near the edge, the pit is converted into a lateral 

 indentation of the summit — the central folds are few. In Pseudo- 

 chirus (lemuroide*^ mongan, caudivolrulus) the marginal indents 

 are similar — the central folds more numerous. In Petaurista and 



