SEA-FISHERIES LABORATORY. 271 



and is seen as a slender nerve passing forwards over the 

 eye and somewhat near the skin, which it supplies with 

 general cutaneous fibres. It is not free from lateral line 

 fibres, as shown by the little plexus innervating sense 

 organs 3 to 5 of the supraorbital canal. 



The Truncus infraorbitalis (t. inf.), consisting of the 

 T. maxillo-mandibularis + lateral line and communis 

 components from the facial, arises ventrally from the 

 Grasserian ganglion and passes sharply downwards and 

 forwards. It soon splits into two large nerves as follows : 



3. R. maxillaris superior (or R. maxillaris— mx. v.) . — 

 Closely accompanied by a lateral line component from the 

 facial, which will be described in its proper place. It 

 consists largely of general cutaneous fibres, and possibly 

 also transmits some communis vii. fibres. It passes 

 straight forwards across the orbit on to the upper jaw, 

 and gives off a cutaneous twig in front, accompanying the 

 lateral line component, and is finally distributed mostly 

 to the skin of the anterior part of the face. 



4. R. maxillaris inferior (or R. mandibularis— 

 man. v.). — May also contain a communis component. 

 Divides at once into a smaller upper and a larger lower 

 branch. Both give off some purely motor branches, and 

 the nerve is thereafter continued obliquely downwards 

 and forwards across the orbit in two sections — a smaller 

 upper and a larger lower. The former contains a few 

 motor fibres, the latter more of the same, the remaining 

 fibres being of small calibre and staining very faintly. 

 The upper one bifurcates, each half containing both the 

 sensory and motor fibres, and terminates in the posterior 

 region of the orbit. The lower one passes forwards, 

 following the ventral curve of the orbit, and giving off 

 several branches on the way, on to the lower jaw, on which 

 it ends. At about the anterior region of the orbit it gives 



