126 



THE SKULL OF MARSUPLVLS 



the original statement of Owen was correct, at least in part. It 



is at most feehly developed (see Fig. 58, p. 118). 



As to skeletal characters, the Marsupial skull has on tlie 



whole a tendency towards a permanent separation of liones 



usually firmly ankylosed. Thus the orbitosphenoids remain 



distinct from the pre- 

 sphenoid. The palate is 

 largely fenestrated, a return 

 as it were — says Professor 

 Parker — to the Schizogna- 

 thous palate of the bird. 

 The mandil)le is inliected ; 

 this familiar character of 

 the Marsupials goes back 

 to the earliest representa- 

 tives of the order in Meso- 

 prsph zoic times (see p. 96); but 

 it is not absolutely uni- 

 versal, being al)sent from 

 the much weakened skull 

 of Tarsi pes. On the other 

 hand, the intiectiou is nearly 

 as great in certain Insecti- 

 vores, in Otoryon, etc. The 

 malar always extends l»ack 

 to form part of the glenoid 

 cavity. The shoulder girdle 

 has lost the large coracoid 



bds.oc 



Fti;. 62. -Skull of Rock Wallaby {Pdn.gule 

 penlciUata). (Ventral view.) «//, Alisphenoid; 

 has.oc, basi-occipital ; has.sph, basi- sphenoid ; 

 e.'.'.oc, e.\-occipital ; /«, iugal ; ma.r, nia.xilla : x- ix/r 4^ " ti • i 



pal, palatine ; par.oc, prroccipital ; p.ma:l ^t MonotrcniCS : thlS l)one 

 preniaxilla ; pr.sjih, presplienoid ; 2)f, ptery- 

 goid ; sip squamosal ; /y, tynipanie. (From 

 Parker and Haswell's ZonUiijij.) 



has the vestigial character 



that it possesses in other 



Eutheria. The clavicle is 



present except in the Peramelidae. A third trochanter up'bn 



the femur seems to be never present. 



The Marsupials cannot be regarded as an intennediate stage 

 in the origin of the Eutheria for a number of reasons. In the 

 first place, the nature of their teeth shows them to be degenerate 

 animals ; one set, whether we regard it as the milk or permanent 

 dentition, has become vestigial. The recent discovery of a true 

 allantoic placenta in PeramrJcs removes one reason for regarding 



