88 ALUS. [Vol. II. 



morphologically forward to the dorsal branch of the next 

 anterior nerve. 



The ventral branch of the nerve of the fifth segment sends 

 a large branch forward to join a nerve formed by the fusion of 

 the nerves of the three next anterior segments. From the 

 large nervous trunk, so formed, a branch is sent downward 

 and forward to the sternohyoideus muscle, the remainder of 

 the trunk, as the nervus pterygialis, continuing downward 

 and backward to the pectoral fin. After giving off this 

 anterior branch, the main nerve continues downward and 

 enters the ventral fin, no other branch being sent from it to 

 the pectoral fin. 



The ventral branch of the nerve of the sixth segment sends 

 an important branch forward to join the nerve of the fifth seg- 

 ment, the branch joining the latter nerve distal to the point 

 where the anterior branch of that nerve is sent forward to join 

 the three next anterior nerves. As this branch thus forms 

 part of a plexus which is evidently the so-called brachial plexus 

 of the fish, it is highly probable that the nerve of the sixth 

 segment takes part in the innervation of the pectoral fin. 

 After giving off this branch the main nerve continues down- 

 ward and enters the ventral fin. 



The nerve of the seventh segment has no perceptible con- 

 nection with the anterior nerves. It thus, in all probability, 

 takes no part in the formation of the brachial plexus, and 

 consequently no part in the innervation of the pectoral fin. 



Anterior to the nerve of the fifth muscle-segment, between 

 it and the vagus, there are in Scomber but three nerves. The 

 two posterior ones are represented by both dorsal and ventral 

 roots ; the anterior one by a ventral root only. All of these 

 roots traverse foramina in the occipitale laterale, the foramina 

 lying close together and varying in number from two to five. 

 The one or two foramina of the posterior nerve were always 

 found separate and distinct from those of the two anterior ones, 

 and they lay posterior to, and close to, the third intermuscular 

 septum. Whether the foramina of the two anterior nerves 

 also lay posterior to this septum, or were traversed by it, or 

 lay anterior to it, was not noted. The five roots issue close 



