158 EUWAKD PHELPS ALLIS, JDN. 



authors^ in that one branch of my nerve quite certainly does 

 not pierce the sclerotic. This branch is thus quite probably 

 not a ciliary nerve, and would seem to correspond approxi- 

 mately to the lachrymal nerve of human anatomy. 



As it gives off this first branch the ophthalmicus profundus 

 issues from the interval between the two bundles of the rectus 

 internus, and then continues its forward course, passing- 

 downward and forward across the postero-lateral surface of 

 the internus muscle, and then ventral to that muscle. When 

 it reaches the ventral edge of the muscle it gives off a 

 delicate branch which separates into two parts, and possibly 

 into three, for a line of tissue here continues the course of the 

 branch, and I am unable to tell whether it is partly nervous 

 or wholly of fibrous or connective tissue. The two parts of 

 which I am sure form the radix longa, and run downward 

 and backward to the ciliary ganglion. The other one, if it 

 be a nerve, must be a part of the ciliaris longus, for it runs 

 downward and forward to join the optic nerve. 



Anterior to the point where the radix louga is thus given 

 off, the ophthalmicus profundus continues its forward course, 

 lying lateral or ventro-lateral to the ventral edge of the 

 rectus internus. In this position it passes dorsal to the optic 

 nerve, and immediately beyond that nerve gives off a large 

 branch which runs forward and outward to the antero-ventral 

 aspect of the eyeball. There it pierces the outer membranous 

 envelope of the eyeball, and continuing forward between that 

 membrane and the sclerotic diminishes gradually in size, and 

 finally disappears without ever piercing the sclerotic, so far 

 as I could determine. It lies, in this terminal part of its 

 course, slightly lateral to the ventral edge of the rectus 

 internus, this position thus seeming similar to that occupied 

 by the ciliai'is brevis of Herrick's descriptions of Menidia 

 (32, p. 224), just as, or before, that nerve pierces the sclerotic. 

 If the nerve in Mustelus does not pierce the sclerotic, as 

 my observations would seem to indicate, it cannot be the 

 homologue of Herrick's nerve, for it \/ould not be a ciliary 

 nerve. If it be not such a nerve it would seem to corre- 



