x^Va 



M1> 



29 



expanded, the hgemal 

 one, H, is contracted ; 

 and, in the expanded 

 neural arch, the auto- 

 genous diapophyses, dd^ 

 are wedged between the 

 neurapophyses, ?i, and 

 the enormously ex- 

 panded neural spine, 

 ns. More commonly, 

 as in the example from 

 the raven's thorax (Fig. 

 5), the haemal arch, H, 

 is much expanded, the 

 neural one, ^, contract- 

 ed; and in the expanded 

 hgemal arch, the para- 

 pophysis, 2?, here exo- 

 genous, is wedged be- 

 tween the centrum, C, 

 and the pleurapophysis, 

 pi. Sometimes, again, 

 as is exemplified in the 

 tail of the crocodile and 

 of many other animals, 

 both neural and haemal 

 arches are alike con- 

 tracted ; the pleurapo- 

 physes, pl^ being ex- 

 cluded from the latter, 

 and standing out as con- 

 tinuations of the conflu- 

 ent diapophyses, d^ and 



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