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MANUAL OF ELEMENTARY ZOOLOGY 



seen to be two ophthalmic nerves, one of which — the 

 superficial ophthalmic — passes above certain of the eye 



Fig. 270. — The central nervous system of a skate. 



cd. f Cerebellum; cer., cerebrum; m.o., medulla oblongata; md.m., mandibular 

 muscle ; olf.L, olfactory lobe ; olf.o. t olfactory organ ; olf.st., stalk of olfactory 

 lobe; op.l.) optic lobe; os* t superior oblique muscle; r.6., resliform body; 

 r.e. t r.i.j r.s,, external, internal, and superior recti muscles; s6., spiracle; 

 sp.c, spinal cord; sp.n>, spinal nerves (converging to form brachial plexus); 

 //.-jr., cranial nerves; r.meK, V.nvx.^ mandibular and maxillary branches 

 of fifth nerve ; V.op., superficial ophthalmic branch of fifth nerve, with which 

 is united that of seventh nerve; l F .o/>'., deep ophthalmic nerve; Vll.b., 

 inner buccal, VII.b\ outer buccal, J '//.cm., Vll.hd., Vll.i.m^ Vlf.p.sp.^ 

 VIl.paL, y/I.pt.sp., external mandibular, hyoidean, internal mandibular, 

 prespiracular, palatine, and postspiracular branches of seventh nerve; X.g.s., 

 XI., Xv. t gill slit, lateral line, and visceral branches of tenth nerve (vagus). 



muscles (the internal and superior recti and the superior 

 oblique), whereas the other — the deep ophthalmic (ophthal- 



