v.] MARSUPIALIA. 65 



spines inclined forwards, long, broad, and flat transverse 

 processes pointing forwards and downwards, well developed 

 metapophyses and rudimentary anapophyses. 



In the MARSUPIALIA, the number of thoracico-lumbar 

 vertebrae is invariably 19, although there are some apparent 

 exceptions, in which the last lumbar assumes the form of a 

 sacral vertebra. The rib-bearing vertebrae are always 13, 

 except in the Koala (Phascolarctos), which has but 1 1, and one 

 species of Wombat (Phascolowys vombatus), which has 15. 

 The Hairy-nosed Wombat (P. latifrons] has the ordinary 

 number. 



In the Kangaroos, the lumbar vertebrae have largely 

 developed metapophyses and anapophyses, and moderate- 

 sized transverse processes much curved forwards. 



In the running and jumping Bandicoots (Perameles) the 

 lumbar vertebrae have very slender, long, forward-directed 

 spines, and long transverse processes. In the climbing 

 Opossums (Didelphys), on the other hand, the spines are 

 very short and broad from before backwards. 



The MONOTREMATA agree with the Marsupials in the total 

 number of trunk vertebrae, but those that bear ribs are more 

 numerous, viz. 16 in Echidna, and 17 in Ornithorhynchus. 



The spinous and transverse processes are very short, 

 and the ribs have no articulation with the latter, but are 

 attached to the bodies only, the greater part of the articular 

 surface being below the neuro-central suture, the reverse of 

 what occurs in the higher Mammals. In the thoracic ver- 

 tebrae the canals for the exit of the spinal nerves perforate 

 the neural arch. 



