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. is. 



The haemal arch, fig. 81, 20-22, 11, is drawn forward, so that its 

 apex, 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 

 fig. 84, 20. The hsemapophyses are simple, and their essential 

 part, intervening between the pleurapophysis and haemal spine, is 



Side view of cranial vertebrae and sense-capsules ; the hremal arches, H h, in outline, Cod (Morrhiut vulgaris) 



short and thick ; but they send a long process 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 fishes, and a second downward and backward, and 

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

 ' premaxillary,' ib. 22. Each pleurapophysis supports a ' diverg- 

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

 one, wdiich fixes the present haemal arch to the succeeding one, 

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

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

 its neural arch is the ' rhinencephalic ; ' its haemal arch, forming 

 what is termed the upper jaw (maxilla), is called the ' maxillary ' 

 arch and appendages. 



On reviewing the arrangement of the bones of the foregoing 

 segments, one cannot but be struck by the strength of the arches 

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



