SEA-FISHERIES LABORATORY- 305 



double, the posterior of which bears a very small ganglion. 

 No exchange of fibres between the sympathetic and the 

 vagus was observed. 



In the cranial sympathetic only 7 ganglia were found 

 instead of 8. When the cord reaches the glosso- 

 pharyngeus, instead of becoming attached to the ventral 

 border of the ganglion and subsequently to that of Jacob- 

 son's anastomosis, it passes upwards internally to the ixth 

 and becomes opposed to its upper division. This is due 

 to the fact that when the ixth splits it forms a dorsal 

 Jacobson's anastomosis and a ventral post-trematicus, 

 instead of the reverse as on the right side, and the 

 sympathetic always accompanies the former. Ganglion 5 

 lies quite clear of and above the glossopharyngeus, in 

 striking contrast to the condition on the other side. As 

 the cord passes through the jugular foramen it is for a 

 time very tightly wedged into the angle formed by the 

 outgoing post-trematicus vii. and the hyomandibular 

 trunk. We could not determine whether there was any 

 exchange of fibres between the sympathetic and the facial 

 nerve, but if present it is not obvious. There is a large 

 R. communicans (com. v.') to the base of the T. maxillo- 

 mandibularis. 



The combined sympathetic and profundus nerve when 

 they enter the eye muscle canal lie just above the ciliary 

 ganglion. Instead, however, of passing straight down to 

 the ganglion, as on the right side, they curve round the 

 left rectus externus muscle, and describe an almost com- 

 plete circle before reaching the ganglion. The few fibres 

 forming the Radix longa and the sympathetic join with 

 the fibres leaving the ciliary ganglion to form the R. 

 ciliaris brevis. It is doubtful whether many of them 

 enter the ganglion at all on this side. There are no other 

 differences of importance between the two sides, 



Y 



