272 ALUS. [Vol. XVIII. 



This branch, which is less stout at its origin than the anterior 

 continuation of the main nerve, runs forward on the outer surface 

 of the geniohyoideus, or shghtly buried in it, and, as already 

 described, anastomoses completely, in the middle line of the head, 

 with its fellow of the opposite side. The anterior end of this mid- 

 ventral trunk is joined, on each side of the head, by the trigeminal 

 branch that I have described as r. gh, those two nerves and the 

 two facial branches anastomosing so completely that their respec- 

 tive limits can not be determined. From the united nerves branches 

 are sent to both divisions of the geniohyoideus. In Mcnidia it is, 

 according to Herrick, as already stated, the trigeminus and not 

 the facialis that innervates this muscle. 



The Ramus Palatinus Facialis {pf) leaves the main truncus 

 facialis, as already described, while that truncus is still inside the 

 trigemino-facial chamber of the petrosal. It runs directly down- 

 ward, or downward and forward, and immediately leaves the 

 chamber by the dorsal opening of the palatine canal. It then 

 traverses that canal, and issuing from its ventral end enters the 

 anterior end of the eye-muscle canal. From there it runs for- 

 ward, ventral to all the muscles of the eyeball, lying at first along 

 the lateral edge of the parasphenoid, and then slightly dorsal to 

 that edge. Near the hind edge of the antorbital process of the 

 skull it turns sharply laterally and forward, and separates into 

 two parts. One of these parts turns directly laterally, toward 

 the lateral edge of the palato-quadrate arch, and was lost in the 

 tissues there. It is a delicate nerve and is perhaps the homologue 

 of a part of the ramus palatinus posterior of Ainia. The other 

 and principal part of the nerve turns directly forward, along the 

 ventral surface of the skull, and could be traced internal to the 

 vomer toward the anterior end of that bone, as all, or part, of the 

 ramus palatinus anterior facialis. No branches of either nerve 

 could be traced far enough to determine whether there was or was 

 not an anastomosis with the maxillaris superior trigemini, as 

 there was in Amia. 



8. Nervus j^custicus. 



No special study was made of the ear of Scomber, and the two 

 views given of it (Figs. 67 and 68) are intended simply to show 

 its general form and the distribution to it of the several branches 



