118 STRUCTURE AND CLASSIFICATION OF BIRDS 



approach each other in the middle line, as in Psophia. 

 Sometimes a number of these processes unite to form a 

 canal ; this occurs in the Steganopodes, and most Herodiones 

 (but not in Scopus umbretta) ; but the classificatory signifi- 

 cance of the fact is marred by the occurrence of a similar 

 canal similarly formed in some Picida3, and in the case of 

 one vertebra in the parrot, Eclectics polychlorus. 



It is sometimes the case that the last of the catapophyses 

 is consolidated into a thick process, which is bifid at the 

 extremity ; this process forms a transition to the following 

 haemapophyses (or hypapophyses) . These latter are un- 



ns 



FIG. 66. ATLAS OF 

 EMU (AFTER 



MIVAKT). 



in', articular surface ; 

 , vertebrarterial 

 caual ; lip. liyper- 

 apophyses. 



FIG. 67. Axis OF EMU (AFTER 

 MIVART). 



o, odontoid process : ., neural spine ; 

 :, anterior zygapophyses ; pi, 

 pleural lamella ; pc, articular sur- 

 face ; Aw. hypapopliysis : lip, kyper- 

 apophysis. 



FIG. 68. ATLAS OF 

 CASSOWARY (AFTER 

 MIVART). LETTERS 

 AS m FIG. 66. 



paired median processes, which commence upon the cervical 

 vertebrae, and extend for a variable distance back along the 

 dorsal vertebrae. They are very feeble, and sometimes 

 limited to the cervical region, in the Herodiones. They are 

 most highly developed in Sphenisci, Colymbi, Alcse, and some 

 Anseres, being in these cases continued to the end of the 

 dorsal series, and even being found upon some of the lumbar 

 vertebrae. In many cases these processes are flattened out 

 at the free end like an inverted T, or are trifid at the same 

 place. This is seen to be due to the gradual shifting in 

 position of a posterior set of catapophyses, which at first are 

 at the sides of, and far from, the haemapophyses, but 



