SEA-FISHERIES LABORATORY. 285 



consists very largely of communis fibres from the Lobus 

 vagi, but also contains motor and cutaneous components. 

 In its intracranial course it is almost entirely covered by 

 the root of the lateralis, and before it reaches its foramen 

 in the skull, and whilst passing through it proximally, it 

 bears a smallish ganglion distinctly separated from the 

 other vagus ganglia. This is the jugular ganglion (Jug. g.), 

 also found by Herrick in Gadus and Menidia. It is the 

 ganglion of the cutaneous fibres of the vagus, and forms 

 typically the R. cutaneus dorsalis vagi, and the R. oper- 

 culars vagi. 



R. operculars vagi (r. op. x.). — This is given off 

 directly the vagus leaves the skull, and at its origin is 

 very closely opposed to the base of the R. supratemporalis 

 vagi (see chart), but it does not fuse peripherally with it, 

 as in Gadus according to Herrick. It passes forwards, 

 and divides into antero-dorsal and postero-ventral branches 

 supplying the skin of the opercular and supra-opercular 

 regions. It contains both light and heavily myelinated 

 fibres. After giving off this ramus, the vagus swells into 

 the large ganglionic complex (g. x. 2-5), of which only the 

 first ganglion (g. x. 1) is completely distinct. 



1. — Truncus branchialis primus Vagi (t. x. 1). 



Arises from the dorsal aspect of the vagus on 

 its inner surface. It passes inwards and backwards 

 towards the first spinal sympathetic ganglion, to which 

 it becomes closely opposed. It then bends forwards 

 and downwards, and at once swells into its large 

 ganglion (g. x. 1), which is quite distinct from the other 

 vagus ganglia, as is general among Teleosts. The motor 

 component of the truncus passes over the external surface 

 of the ganglion. Distal to the latter the truncus passes 

 downwards and forwards and divides into an upper pre- 



