302 



ANATOMY OF VERTEBRATES. 



fig. 196, 1) : it escapes by the foramen or anterior notch of the 

 alisphenoid, in advance of the fifth nerve. 



This nerve, the trigeminal, enormous in all Fishes, from the 

 Lancelet to the Lepidosiren, rises, often by two or more roots, from 

 the restiform, or from the anterior angle between the olivary and 

 restiform tracts ; in some fishes from a special ganglion or enlarge- 

 ment of that part of the medulla oblongata, as in the Herring, fig. 

 184, i: in a few (Conger, Lump-fish) by a smaller origin resolved 

 into several roots. The trigeminus shows well its spinal (myelonal) 

 character in Fishes, only its double root is more deeply buried in 

 the medulla oblongata. In the Cod, fig. 201, the non-ganglionic 

 portion is shown at i, the roots of the ganglionic portion at 2, 2. 

 On the left side the non-ganglionic portion is separated and turned 

 back : on the right side its divisions are seen accompanying the 

 first, , second, b, and third, c, branches of the trigeminal. The 

 fourth branch, d, is also composed of both portions of the nerve : 

 the fifth branch, e, is exclusively from the ganglionic portion. 

 The trigeminal is in close contact with the acoustic nerve, at their 



202 



Brain and fifth nerves of the Ray. co'vilt. 



origins. In Coitus, Blennius, Cobitis, and Leudscus, the ganglionic 

 or dorsal roots recede from the ventral ones, as they penetrate the 

 medullary substance. The non-ganglionic roots in the Blenny 

 join the facial and glossopharyngeal. Of the five roots of the 

 trio-eminal in the Sturgeon, the first, second, and fourth form a 



