130 NERVE COMPONENTS OF BONY FISHES. 



trunks the coarse fibres and the fine fibres can be sepa- 

 rately followed, but it is often not possible to keep the two 

 classes of fine fibres (communis and general cutaneous) 

 distinct throughout their courses, nor always the two 

 classes of coarse fibres (lateralis and motor). Neverthe- 

 less their terminal relations enable us to infer their courses 

 in the trunks with suiScient accuracy. 



I. — The Roots and Ganglia of the Facialis. 



The facial has four roots emerging at the same trans- 

 verse level, a ventral motor root, widely separated from 

 the others, ventral and dorsal lateralis roots and the com- 

 munis root, emerging between the two last. The last 

 three issue high up towards the dorsal side of the 

 oblongata. 



/. — TJie Motor Root. 



The motor VII nucleus lies near the median line in con- 

 tact with its fellow of the opposite side and separated 

 from the fourth ventricle by fibres of the fasciculus longi- 

 tudinalis dorsalis only. The cells are large and are 

 grouped on each side in two clusters, from each of which 

 a strong tract of fibres (secondary tracts or dendrites ?) 

 runs out laterally and ventrally into the lateral white col- 

 umns. In connection with the more mesal one of these 

 tracts are fibres which seem to run from the fasciculus 

 longitudinalis dorsalis to the VI root. The motor VII 

 nucleus occupies the position of the commissura accessoria 

 of Mauthner, which is interrupted in this region. 



From both parts of this nucleus facialis fibres run dor- 

 sad and form a large, close bundle on the lateral aspect of 

 the fasciculus longitudinalis dorsalis. It lies just ventrally 

 of the bundle of fibres derived from the nucleus ambiguus. 



