XII 



PHYLUM CHORDATA 



379 



Besides the lateral line, which is probably the seat of a 

 delicate tactile sense, and the tongue, which is presumably 

 an organ of taste, there are the three pairs of characteristic 



FIG. 212. Scyllium catulus. Dissection of the brain and spinal nerves from the 

 dorsal surface. The right eye has been removed. The cut surfaces of the 

 cartilaginous skull and spinal column are dotted. The ophthalmicus profundus 

 and the buccal branch of the facial are not represented, cl.r-cl.5, branchial 

 clefts ; ep. epiphysis ; ext. rect. external rectus muscle of the eye-ball ; gl, ph. 

 glossopharyngeal ; hor. can. horizontal semicircular canal ; hy. mud. I'll, hyo- 

 mandibular portion of the facial ; in/ obi. inferior oblique muscle ; int. rect. 

 internal rectus muscle ; lat. vag. lateral branch of vagus ; m.r. I '. maxillary 

 division of the trigeminal ; olf. c/>s, olfactory capsule ; olf. s. olfactory sac ; 

 oph. V. VII. superficial ophthalmic branches of trigeminal and facial ; path. 

 fourth nerve ; pi. VII. palatine branch of facial ; sp.co. spinal cord ; sp., spir. 

 spiracle ; j. rect. superior rectus muscle ; s. olb. superior oblique ; vag. vagus ; 

 vest, vestibule. (From Marshall and Hurst.) 



sensory organs, the structure and position of which are very 

 characteristic of vertebrates. These are the olfactory organs, 



