100 



ANATOMY OF VERTEBRATES. 



' olfactory lobes' ; the special name of such neurapophysis is ' pre- 

 frontal,' ib. 14. The neural spine is usually single, sometimes 

 cleft along the middle; it is the 'nasal,' ib. 15. 



The ha3mal arch, fig. 81, 20-i2, H, is drawn forward, so that its 

 apexi as well as its piers, are joined to the centrum (vomer), and 

 usually also to the neural spine (nasal), closing up anteriorly the 

 neural canal. The pleurapophyses are simple, short, sending 

 backward an expanded plate ; they are called ' palatines,' ib. and 

 fin-. 84, 20. The hasmapophyses are simple, and their essential 

 part, intervening between the pleurapophysis and hajmal spine, is 



81 



side view &f cranial vcrtelirie ami senf-e-capsules ; tlie biumai arelic?, H n, in outline, Cotl (^[ui^rJlua i-uJiroris) 



short and thick ; Ijut they send a long ])rocess backward ; this 

 element is called 'maxillary,' ib. 21. The haemal spine, cleft 

 at the middle line, sends one process upward of varying length 

 in different fislies, and a second downward and backward, and 

 its under surface is beset with teeth in most fishes : it is called 

 ' premaxillary,' ib. 22. Each pleura[)ophysis supports a ' diverg- 

 ing appendage,' consisting commonly of two bones : the outer 

 oue, which fixes the present hajmal arch to the succeeding one, 

 is called 'pterygoid,' figs. 75, 81, 24; the inner one is the ' ento- 

 pterj'goid,' ib. 23. The entire segment is called the ' nasal vertebra ;' 

 its neural arch is the ' rliinencephalic ; ' its hremal arch, forming 

 what is termed the upper jaw (ma.riUa), is called the ' maxillary ' 

 arcli and appendages. 



On reviewing the arrangement of the bones of the foregoing 

 segments, one cannot but be struck l)y the strength of the arches 

 which protect and encompass the brain, and by the efficiency of that 



