236 ALUS. [Vol. XVIII. 



outward along the edge of that muscle. The terminal branch of 

 the nerve that supplies the rectus internus runs outward along, 

 and innervates, the rudimentary muscle that lies immediately dor- 

 sal to, and seems to form part of, the internus. 



The ventral portion of the inferior division of the nervus runs 

 downward, posterior to the rectus inferior, and then forward ven- 

 tral to that muscle, and ventral to the rectus internus, and enters 

 and supplies the obliquus inferior. 



The inferior division of the oculomotorius of Scomber thus sup- 

 plies the same three muscles that it does in Amia, and it and its 

 branches have the same relations to the several muscles of the eye- 

 ball and to the nervus opticus that they have in Amia, with the 

 single exception of the branch that innervates the rectus internus. 

 That branch, in Scomber, lies dorsal to the rectus inferior, while 

 in Amia it lies ventral to that muscle. Just what this difference is 

 will be readily understood if it be supposed that the rectus inferior 

 instead of the rectus internus had, in Scomber, acquired an origin 

 in the eye-muscle canal, the inferior muscle thus passing, at its 

 origin, ventral to the rectus internus instead of dorsal to it. The 

 arrangement in Scomber would then be exactly the same as in 

 Amia excepting only in the order in which the branches that inner- 

 vate the internus and inferior leave the inferior branch of the ocu- 

 lomotorius ; or, otherwise stated, the innervation would be exactly 

 the same, in the two fishes, if the inferior muscle of the one were 

 an internus in the other. Sketches that I have of the eye muscles 

 of Esox, Gadiis and Conger, but which I have not yet controlled, 

 show that that branch of the oculomotorius that supplies the rectus 

 mternus in those fishes has the same position, relative to the rectus 

 inferior, that it has in Scomber. This arrangement may, there- 

 fore, be characteristic of all teleosts, and hence have some special 

 significance. 



The ciliary ganglion, in Scomber, is related to those two 

 branches of the inferior division of the oculomotorius that supply 

 the recti internus and inferior, rather than to the entire inferior 

 division of the nervus. This will be fully described in connection 

 with the nervus profundus. 



