40 



ANATOMY OF VEETEBRATES. 



the back part, and answering to the ^ hypapophysis ' in lizards ; 

 the other parial, developed from the under part of the vertebrar- 

 terial canal, answering to parapophyses, bent or directed down- 

 ward, after coalescing with the pleurapophysis. In a Vulture 

 ( Gyps fulvus), the latter inferior processes begin at the sixth cer- 

 Adcal, and are continued to the thirteenth ; the hypapophysis 

 begins at the second, and is continued to the fifth, where it is 

 reduced to a low ridge. In the Guillemot the hypapophysis 

 exists as a ridge or process in all the cervicals. In the Apteryx 

 the single hypapophysis for the attachment of the longus colli 

 anticus is present in the last three vertebrae, as in the contiguous 

 dorsals. The parapophysial arch for the protection of the carotid 

 arteries is most complete in the twelfth cervical, but the two sides 

 of the arch are not anchylosed together ; the interspace progres- 

 sively increases in the eleventh, tenth, and ninth vertebrae, and 

 the groove widens and is lost at the fifth vertebra. In many 

 birds the parapophyses after forming the sides of a wide canal in 

 the middle cervicals, converge and unite to 

 inclose a haemal canal, as in the lower cervical 

 vertebra of the Pelican, fig. 25. 



The neural arch in most of the cervicals 

 developes, in addition to the spine, ib. ns, 

 zygapophyses, ib. z, and diapophyses ib. t, 

 also anapophyses, or tubercles, above the pos- 

 terior zygapophyses. The arch is, in some 

 A^ertebra, strengthened by bony plates, one 

 of which may be specified as ' interzygapo- 

 physial,' and this may be perforated vertically, as in the second, 

 third, and fourth cervicals of the Hornbill {^Biiceros), and in 

 the third and fourth cervicals of the Vulture, and many other 

 birds ; the neural arch thus becomes remarkable for its breadth, 

 and the square or quadrate platform of bone from which the 

 small and short neural spine rises. In one or more succeeding 

 vertebrae the incomplete ' interzygapophysial' bar projects back- 

 ward as a process or tubercle from the prezygapophysis. The 

 prezygapophyses look upward and inward ; the postzygapophyses 

 downward and outward ; the neural spine is feebly developed, 

 if at all, in the middle of the cervical region ; it is most con- 

 spicuous in the second to the fifth, and again in the last two or 

 three cervicals. In the Apteryx it is thick and strong in the 

 second, but progressively diminishes to the seventh, cer\dcal, 

 where it is reduced to a mere tubercle ; from the eleventh it 

 progressively increases to the last cervical, in which it presents 



Cervical vertebra, Pelican. 



