THE CRANIAL NERVES AND LATERAL SENSE ORGANS OF FISHES. 135 



the two parts above unite and the fibres are almost immediately shuffled into two 

 bundles — a posterior and an anterior — described with the buccal trunk. The origin of 

 the facial proper fibres is mentioned in the description of the facial ganglion. The 

 lateral line fibres of the hyomandibular trunk seem to be derived from the ventral 

 portion of the lateral line ganglion. 



In front of the liyomandibular the trigeminal ganglion lies partly within the cranium 

 and partly outside it, the orbital vein separating the dorsal trigeminal from the ventral 

 facial ganglion. The maxillo-mandibular -|- buccal trunks issue together from the 

 trigeminal ganglion. The former is connected with the trigeminal ganglion, and there 

 cannot be the least doubt that the latter passes upwards and backwards through the 

 same ganglion, and arises, in common with the superficial ophthalmic lateral line nerve, 

 from the dorsal pcn-tion of the lateral line ganglion. Some of the trigeminal ganglion 

 cells extend along the dorsal border of the maxillo-mandibular trunk. In front of the 

 exit of the raaxillo-mandilnilar + buccal trunk, the trigeminal ganglion tapers down and 

 gives off" the superficial ophthalmic division of the trigeminus which accompanies the 

 lateral line nerve of the same name as described below. 



The facial ganglion is perfectly distinct from any other part of tlie complex and lies 

 entirely outside the skull. It commences anteriorly above the orbital vein, and 

 immediately ventral to the trigeminal ophthalmic, passing down\^ards and backwards, 

 and increasing in size so as to lie external to the orbital vein, and ventral and external 

 to the anterior extremity of the trigeminal ganglion. At this region a thin strand 

 pass(!s downwards externally and connects the dorsal with a ventral portion, which lies 

 immediately under the orbital vein. The ventral portion, therefore, does not extend as 

 far forwards as the doi'sal portion, whilst the latter only extends as far back as the 

 maxillo-mandibular + buccal trunk — at which point it ceases to exist. The ventral 

 portion, however, passes backwards under the orbital vein and internal to the above 

 trunk. Internal to this ventral portion the most ventral fibres of the hyomandibular 

 trunk pass downwards and outwards under the orbital vein and enter into relations with 

 the facial ganglion. The first branch to be given off' from these fibres passes through 

 the inner region of the facial ganglion, turning inwards, downwards, and forwards, and 

 passing among the muscles of the alimentary canal. The next branch passes almost 

 through the middle of the ganglion and courses forwards external to the previous 

 blanch. The third and largest branch passes obliquely through the centre of the 

 ganglion, turns inwards, and then divides to form two large nerves — one of which passes 

 forwards and the other backAvards. The forward division again divides, and represents 

 the true palatine branch of the facial nerve and its two divisions, the anterior and 

 posterior palatine nerves described by Allis in Amia. The posterior division passes 

 backwards and slightly outwards and accompanies the cephalic sympathetic trunk, but 

 lias otherwise no connection with it. It finally takes an upward aud outward turn and 

 passes into the ganglion of the glossopharyugeus. It thus represents the nerve known 

 as Jacobsoii's anastomosis, connecting the facialis with the glossopharyugeus. Tiie 

 remainder of the ventral fibres of the hyomandibular pass outwards with the latter 

 trunk and the facial ganglion, but apparently have no connection with it, and are 



