224 ALUS. [Vol. XVIII. 



its attachment, in Scomber, to the second vertebra and to the 

 horizontal rib that articulates with that vertebra. The nerve that 

 innervates the muscle seg^ment immediately in front of it issues 

 through the foramen that perforates the first vertebra, and this 

 nerve is, apparently, the most posterior one that takes any part in 

 the innervation of the Hypoglossusmusculatur. It is also either 

 the most posterior one, or the next to the most posterior one, that 

 can take any part in the formation of the nervus pterygialis. 



The fifth intermuscular septum of Scomber thus corresponds 

 closely, in its relations to the clavicle and to the spinal and oc- 

 cipital nerves, to the same septum in Ainia. But in Scomber 

 this septum has its attachment to the second vertebra, while in 

 Amia it is attached to the last occipital arch. What this may 

 indicate has already been discussed in an earlier work (No. 6) 

 and will be again referred to in considering the spinal and occipital 

 nerves. 



In front of the fifth muscle segment the septa and segments are 

 incomplete, and the anterior ones irregular also. 



The dorsal portions of the fourth and third septa are regular, 

 the dorso-anterior angles and associated septal pockets of both 

 running forward into the supratemporal groove. The second 

 septum is irregular. It has a large dorso-median pocket ex- 

 tending forward in the line of the temporal groove, and a small 

 dorso-posterior pocket extending backward in the line of the 

 corresponding pockets in the more posterior septa. It has, how- 

 ever, no dorso-anterior pocket, its anterior end being attached 

 in part to the hind end of the bony ridge that separates the tem- 

 poral and supratemporal grooves, and in part extending for- 

 ward along the bottom of the latter groove. The bony ridge that 

 separates the temporal and supratemporal grooves is thus an an- 

 terior extension of the line of the second septum. 



The first septum has but one pocket, the dorso-median one. 

 The septum is attached to the pedicle of the suprascapular, and 

 with that pedicle to the posterior process of the intercalar. From 

 there it runs upward and then mesially along the hind edge of the 

 temporal groove, to the hind end of the posterior process of the 

 exoccipitale. From this line of attachment a large pocket extends 

 forward into the temporal groove. At the dorsal end of the 



