V. KuPFFER, Cranial Nerves of Vertebrates. 321 



compared with the earlier stages, have changed the 

 least. 



Its large principal ganglion, arising typically, lies above 

 the septum between the third and fourth gill pouches and 

 over the fourth pouch itself. The short, stout, single root is 

 mostly fibrillar, but also contains cells, both in the interior 

 and as an envelope outside. It sinks into the cephalo-dorsal 

 angle of the ganglion. The hind point of the approxiniately 

 triangular ganglion extends into the N. lateralis, entirely 

 lacking ganglia, which ends in the caudal half of the trunk in 

 a swelling of the epidermis. The cephalo-ventral angle of the 

 principal ganglion sends out the stout N. branchio-gastricus, 

 rich in cells, which connects itself with the seventh epi- 

 branchial ganglion (numbering from before). Five more 

 ganglia lie behind this in the epibranchial cord. There are 

 thus found in the whole chain, which extends from the eye to 

 behind the eight gill pouches, altogether twelve epibranchial 

 ganglia. 



THE BRANCHIAL NERVES. 



I begin with those lying caudad, where the relations are 

 simplest. The hindmost five branchial nerves have the same 

 relations. Each one arises as a cord from the appropriate 

 epibranchial ganglion, and is connected by means of a second 

 more slender cord with a sympathic ganglion of the spinal 

 system. It proceeds then ventrally into the gill arch and 

 divides into a cutaneous and a muscular branch. The cuta- 

 neous branch is the foremost, and connects itself with a 

 rounded protuberance of the epidermis projecting entad. 

 The muscular branch accompanies the arch of the aorta ven- 

 trad and ramifies further (Fig. 9). The external spiracula 

 (gill openings), which are formed behind the pertaining gill 

 pouch, have arisen. Thus the cutaneous branches are shown 

 to be the rami pra;trematici, and the epidermal prominences 

 small separated ganglia, which I will denote as ganglia prae- 

 trematici. 



