198 NERVE COMPONENTS OF BONY FISHES. 



The branch so. 5 runs close to the trunk, but separated 

 from it by a large blood vessel, and gives off numerous 

 branches for the skin between the eye and the supra-orbi- 

 tal canal. As it approaches the cephalic edge of the eye, 

 it diverges laterally from the trunk and sends several twigs 

 to the cornea {co. 2) and eye-ball. The remaining fibres 

 supply a thickened fold of skin laterally of the nasal open- 

 ings. None were traced to special sense organs, the buds 

 in the cephalic part of this region having a different nerve 

 supply. 



At the level of the fifth canal organ of the supra-orbital 

 line a coarse-fibred branch {so. 6) leaves the trunk to 

 supply this and the fourth organ, these two organs lying 

 very close together, but their nerves passing into the 

 canal through separate foramina in the frontal bone. 



Under the pore between the third and the fourth organs 

 of the supra-orbital canal a branch {so. 7), comprising fine 

 and medium fibres, passes up through a foramen in the 

 bony floor of the canal to the skin of the top of the head, 

 part of the fibres running forward a long distance within 

 the bony canal, finally to emerge to the overlying skin. 



Then follow two coarse-fibred branches {so. 8 and so. g) 

 for the third and second supra-orbital canal organs, each 

 with its special foramen in the frontal bone. 



The trunk meanwhile runs parallel with and close under 

 the canal, being separated from it only by the frontal 

 bone. This bone consists of two broad wings and a short 

 vertical plate, the canal lying at the point of their inter- 

 section. One of the wings runs inward from the canal, 

 over the brain cavity and internasal cartilage, the other 

 outward over the eye, while the vertical plate runs down 

 from the canal along the lateral face of the supra-orbital 

 and internasal cartilages. The supra-orbital trunk runs 



