18 



LABORATORY OUTLINE OF NEUROLOGY 



Examine the gills and determine how they work as organs of 

 respiration, noting the direction of flow of water through them 

 and the mechanism by which this flow is maintained. 



a.ur 



sp.co lal.vag 



Fig. 1. — Dissection of the brain and cranial nerves of the dogfish, 

 Scyllium catulus. The right eye has been removed. The cut surfaces 

 of the cartilaginous skull and spinal column are dotted, cl.l-cl.5, Bran- 

 chial (gill) clefts; ep., epiphysis; ext.rect., external rectus muscle of the 

 eyeball; gl.ph., glossopharyngeal nerve; hor.can., horizontal semicircular 

 canal; hy.mnd.VII, hyomandibular branch of the facial nerve; inf. obi., 

 inferior oblique muscle; int.rect., internal rectus muscle; lat.vag., lateral 

 line branch of the vagus nerve; mnd. V, mandibular branch of the trigeminal 

 nerve; mx. V, maxillary branch of trigeminus; olf.cps., olfactory capsule; 

 olf.s., olfactory sac; oph.Y.VII, superficial ophthalmic branches of the 

 trigeminal and facial nerves; path., trochlear nerve (patheticus) ; pl.VII, 

 palatine branch of facial nerve; s.obl., superior oblique muscle; sp., spiracle; 

 sp.co., spinal cord; spir., spiracle; s.rect., superior rectus muscle; vag., vagus 

 nerve; vest., vestibule. (After Marshall and Hurst, from Parker and Has- 

 well's Zoology.) 



8. Cut through the skin in the middorsal line and reflect it on 

 the right side as a lateral flap, leaving this flap attached at the 



