THE SKATE. 79 



206. The distal ends of the olfactory lobes (Fig. 22, o/f\ 

 each forming a slightly convex white band on the dorsal 

 surface of the corresponding nasal sac. 



XLIV. Remove one of the nasal sacs, and note 



207. Its cup-like form, the cavity being open below. 



208. The ridges into which its lining of mucous mem- 

 brane is raised : they are arranged in two rows at right 

 angles to a central ridge. 



XLV. Remove the eye with its remaining muscles, and 

 set it aside for future examination. 1 Dissect out 



209. The second division of the fifth nerve (Figs. 22 and 27, 

 F 2 ), arising mainly from the posterior fasciculus mentioned 

 in 1 86, but also receiving fibres from the anterior fascicu- 

 lus : it passes forwards and slightly outwards, and divides 

 into two chief branches, an internal, the palato-nasal 

 nerve (F 2a ) and an external, the maxillary nerve ( F 2b ) 

 the former passing directly forwards alongside the cranial 

 wall and beneath the eye muscles, and the latter passing 

 outwards and forwards towards the antorbital cartilage 



(S 35). 



210. The third division of the fifth, or mandibular 



nerve (V 3 ), arising mainly from the anterior, but receiving 

 fibres from the posterior fasciculus : it runs parallel with the 

 common trunk of the second division as far as the bifurcation 

 of the latter, and then takes a course internal to and nearly 

 parallel with the maxillary nerve. 



The three divisions of the fifth nerve supply between them all the 

 anterior part of the head : the orbito-nasal goes to the dorsal region of 

 the rostrum and nasal capsule, and to the gelatinous tissue in their 

 neighbourhood : the palato-nasal to the ventral region of the same parts, 

 as well as to the fronto-nasal process and the nostrils ; it also sends 



1 The eye must be dissected in the fresh condition : for directions see 

 LI I., p. 84. 



