524 



ZOOLOOY 



SECl'. 



reaches the presternum veiitrally. A clavicle is always present, 

 except in the Bandicoots, but may be incomplete. There is never 

 a distinct centrale in the carpus. In the Opossums the ilium has 

 the primitive form of a straight, three-sided rod. In the 

 Kangaroos (Fig. 1131, il.) it is still simple and three-sided, but 

 somewhat curved outwards ; in the rest it is more or less com- 

 pressed. In nearly all the Marsupials there is a pair of epipubic 

 or marsupial bones (Fig. 1131, q)i.) — elongated and compressed 

 bones which articulate posteriorly with the anterior edge of the 

 pubes : in the Thylacine they are represented only by small 

 unossified fibro-cartilages. In the leg the fibula is always well- 

 developed. In the young condition of some Marsupials there is 

 an accessory element situated outside the fibula at its proximal 



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Pio. 1134.— Skull of "Wombat (Phasrolomys womh/U) (hxteral view). Letters as in Fig. 113-2. 

 In addition, ext. av.il. (jpeuing of bony auditory meatus ; cond. condyle of mandible. 



end : this apparently corresponds to a bone known as the para- 

 fibula, which occurs in some Lacertilia, In the Phalangers (Fig. 

 1135) and the Koala there is always a considerable range of move- 

 ment between the fibula and the tibia, comparable in some degree 

 to the movements of pronation and supination of which the radius 

 and ulna are capable in many Mammals. The foot (Figs. 1135, 

 1136), as already stated in the account of the external characters, 

 presents a much greater range of modification than the manus. 



Skeleton of Edentata, — In the Armadillos more or fewer of 

 the cervical vertebra3 are ankylosed together both by their bodies 

 and by their neural arches. In the lumbar region the meta- 

 pophyses are greatly prolonged — longer than the transverse pro- 

 cesses — and support the bony carapace. A remarkable peculiarity 

 of the spinal column in the Armadillos is the fusion of a number 

 of the anterior caudal vertebrae with the true sacrals to form the 

 long sacrum, containing as many as ten vertebrae altogether (Fig. 

 1146). The caudal region is of moderate length; there are 



