110 ON THE PHALANG1STID.E OF THE POST-TERTIARY 



families other than the Phalangistidse, and even with Phascolarctos,- 

 the aberrant genus of that family. As the weight of the animal 

 attested by the fossil is to be reckoned in hundredweights, one could' 

 hardly conceive it to belong to that division of the Phalangistidse r 

 the Petaurists, which are flotant in their leap from tree to tree ; if 

 is, however, satisfactory to find in the fossil no inducement on 

 structural grounds to refer it to that division. Archizonurus was r 

 in short, a true Phalanger, as will be seen from the description. 



The glenoid fossa is elongate and proportionately narrow. 

 Its anterior or rostral two-fifths relatively broad and bat slightly 

 dilated posteriorly — its caudal three-fifths suddenly but very 

 moderately expanding. Its form is thus hardly to be distinguished 

 from that of the Toolah, Phalangista (?) archeri, but it differs from 

 this, and, indeed, from the rest of the Phalangers, in not having 

 its rostral edges brought together and produced at the point into a 

 bicipital tubercle ; the external edge is on the contrary reflected 

 upon the ectal surface of the bone. The coracoid is a thick oval 

 process attached longitudinally by the greater part of its upper 

 side, but so as to leave free a distinct exterior, and a longer interior 

 end ; it is separated from the glenoid fossa by a broad and deep- 

 groove, which, in the middle, is interrupted by a strong ridgo 

 passing from the middle of the posterior edge of the process to the- 

 place of the bicipital tubercle — a well marked groove extending 

 more or less upon the ectal as well as the ental surface adjacent to 

 the root of the process is characteristic of Phalangista and its allied 

 genera — an interrupting ridge is present as a rule, but subject to 

 much variation in its position and direction. Its variability extends 

 to individuals — of U»n scapulas of P. archeri, no two arealike in this- 

 respect. One, however, belonging to this species is sensibly 

 identical with the fossil, and all vary from ic less than do the other 

 species and genera (Cuscus, Pseudochirus). The triceps insertion 

 is into a pit within an elongate triangular depression defined by the 

 parted edges of the ectal and ental surfaces, of which the latter is 

 the more prominent — the insertion has therefore the peculiarity of 

 appearing on the ectal instead of on the ental aspect of the bone as 

 usu il in the Phalangers. 



