266 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



of the fact that the large ventral nerve emerging from the 

 Gasserian ganglion contains lateral line and communis 

 components from the facial, the term T . maxillo-mandibu- 

 laris, which refers to the unsplit BE,, maxillaris and 

 mandibularis V, cannot strictly be applied to it. The 

 cutaneous component of the trigeminus arises from the 

 spinal v. tract, and its ganglion is the Grasserian ganglion. 

 It is distributed to the skin of the face and operculum. 



The second root of the complex (r.l.vii.) belongs 

 wholly to the facial, and consists of 3 roots so closely 

 packed together that it is difficult to separate them by 

 dissection. These roots are the dorsal and ventral lateral 

 line roots and the communis root. The whole arise 

 together at the same level high up on the medulla and 

 much higher than and external to the exit of the 

 trigeminus. The ganglia of the lateral line roots are 

 respectively the dorsal and ventral lateral line ganglia, 

 and that of the communis root is the geniculate ganglion. 

 The dorsal lateral line root splits into the Ramus 

 ophthalmicus superficialis vii. and the R. buccalis vii., 

 whilst the ventral lateral line root is continued into the 

 Truncus hyomandibularis as the R. mandibularis externus 

 vii. The communis root splits into the communis v., R. 

 palatinus vii., the R. Posttrematicus vii. and the R. 

 mandibularis internus vii. Although the three com- 

 ponents in this root are very compacted they retain their 

 individuality under the microscope. The communis root 

 enters the brain first, and then the other two fuse and 

 enter together behind and above it. The communis root 

 in the brain passes at once into the fasciculus communis 

 tract, and the fused two lateral line roots terminate in the 

 tuberculum acusticum. 



The third root of the complex (r.2.vii.) is also 

 entirely facial and constitutes its motor root. It arises 



