670 MR FRANK J. COLE ON THE 



(6) Accessory visceral branch (a) (X 3 G ). — Arises from the prse-branchial, and passes 

 under the third branchial arch downwards and forwards to the pharynx. 



(7) Accessory visceral branch (b) (X 3 7 ). — Also from prse-branchial. This relatively- 

 stout nerve courses downwards and forwards under the third branchial arch, to reach 

 the pharynx in the neighbourhood of the anterior lateral edge of the arch. It might 

 almost be described as an accessory skeletal branch. 



(8) Accessory visceral branch (c) (X 3 s ). — Springs from the accessory skeletal branch 

 X 3 3 , and dips down in front of the fourth branchial arch. It keeps to the anterior edge 

 of the arch, and is distributed to the pharynx dorsally in that region. 



(9) Accessory visceral branch (d) (X 3 9 ). — Arises from the post-branchial, and passes 

 forwards over the fourth branchial arch, external to the other nerves. It is a very 

 slender nerve, and innervates the pharynx near the dorsal anterior edge of the arch. 



Intestinal Nerve (I.). 



This division of the vagus arises as its most posterior root, and soon after leaving 

 the cranium expands into an obvious ganglion. It then passes outwards and backwards, 

 and splits up to form a very complicated plexus on the pharynx and proximal portion 

 of the oesophagus. Several of the bundles unite again to form somewhat large nerves, 

 and these, in their turn, break up into another plexus on the distal portion of the 

 oesophagus and the stomach. The latter plexus was traced as far as the pylorus, i.e., the 

 beginning of the spiral valve. Both plexuses lie on the circular muscles of the oesophagus 

 and stomach, beneath the pigmented serous coat, and are thus easily seen without any 

 dissection. In both the specimens given me by Professor Ewart a very slender nerve 

 was, with much difficulty, traced on to the wall of the sinus venosus, but this was the 

 only branch of the vagus I succeeded in tracing to any portion of the heart. 



Literature. — To Stannius (6) belongs the credit of having first discovered the 

 important fact that the branchial nerves may be continued ventrally on to the pharynx, 

 which continuations, therefore, representing the lingual fibres of the Vth, VTIth, and IXth 

 cranial nerves of higher vertebrates. Gegenbaur (14), however, as is well known, first 

 established its compound nature in Hexanchus, but did not find that each of its 

 components had a separate ganglion.* Jackson and Clarke (16) described a common 

 vagus trunk in Echinorhinus and a common dorsal branch, but the former statement 

 probably needs revision. Ewart (51) repeated this statement for Lasmargus, except 

 that he found a separate ganglion for vagus 1 ; but I understand that Professor Ewart 

 has since found that the vagus trunk of Lsemargus and its compound ganglion may 

 with care, be separated into its constituent branchial and intestinal nerves, each with 

 its separate ganglion. The same, therefore, doubtless applies to Echinorhinus. In 

 1889 Shore and Ewart (50 and 51) independently announced that the vagus of the 



* The division of the vagus attempted by Gegenbaur into representatives of the vagus, spinal accessory, and 

 hypoglossus of higher vertebrates cannot any longer be maintained. 



