142 



occupied by the proximal eud of the second metatarsal bone, which 

 articulates with the os rnagnum. \n the Perameles there are four 

 bones in the distal series, although the hand is less perfect in this 

 than in any other marsupial genus, the three middle toes only being 

 fully developed. In the Petaurists, the carpus is chiefly remarkable for 

 the length of the os pisiforme. It would be tedious to dwell on the 

 minor difFerences observable in the bony structure of the hand in 

 other Marsupiata. I shall therefore only observe that.though the inner 

 digit is not situated likę a thumb, yet that the fingers enjoy much 

 lateral motion; and that those at the outer can be opposed to those at 

 the inner side, so as to grasp an object and perform in a secondary 

 degree the function of a hand. In the Koala the two inner digits are 

 moredecidedly opposed to the three outer ones than in any other climb- 

 ing Marsupial. But some of the Phalanges, as the Ph. Cookii and 

 Ph. gliriformis of Bell, present in a slight degree the šame disposi- 

 tions of the fingers, by which two o'ut of the five ha ve the opposable 

 properties of a thumb— a structure forwhich 'vve seek in vain among 

 the placenta.1 Mammalia, but which we have repeated in the prehen- 

 sile extremities of the Chameleon. 



" The pelvis in the mature Marsupial is composed of the os 

 sacrum, the two ossa innominata, and the characteristic supplemental 

 bones attached to the pubes, called by Tyson the ossa mursupialia, 

 or Janitores marsvpii. 



" We seek in vain for any relationship between the size of the pel- 

 vis and that of the ne\v-born young, the minuteness of \vhich is so 

 characteristic of the present tribe of animals. The diameters both 

 of the area and the apertures of the pelvic canal are considerable, 

 but more especially so in those Marsupialia which have the hinder 

 extremities disproportionally large, as also in the \Vorabat, where 

 the pelvis is remarkable for its ^vidth. The pelvis is relatively small- 

 est in the Petaurists. The anterior bony arches formed by the ossa 

 pubis and the iscfiia are ahvays complete ; and the interspace betvveen 

 these arches is divided, as in other Mammalia, into the t\vo ohturator 

 foramina, by an osseous bridge continued from the pubes to the isckium 

 ou each side of the spnphi/sis. 



" In the Kangaroos, Potoroos, Phalangers, and Opossums, the 

 ischia ofFer an elongated prismatic form. They are straight in the 

 Opossum, but gently curved outvvards in the other marsupial genera. 

 In the Dasyures there is a longitudinal groove widening upwards in 

 place of the angle at the middle of the exterior surface of the ilium. 



" The ilia in the Petaurists are simply compressed from side to 

 side. They are broader and flatter in the Perameles, and their plane 

 is turned out\vards. But the most remarkable form of the ilia is 

 seen in the Wombat, in which they are considerably bent outwards 

 at their anterior extremity. 



" In the Kangaroos and Potoroos the eye is arrested by a strong ' 

 process given o*F from near the middle of the ilio-pubic ridge ; and 

 this process may be observed less developed in the other Marsupiata. 



" The tuberosity of the ischia inclines outwards in a very slight 

 degree in the D.isyures, Opossums, Phalangers, Petaurists, and Pe- 



