242 ALUS. [Vol. XVIII. 



descriptions and of Stannius's, and not a ramus profundus trig- 

 emini ; and a separate profundus root and profundus ganglion 

 must be wholly wanting in Menidia. It is furthermore to be noted 

 that, in all those fishes in which it is properly identified, the ramus 

 ophthalmicus profundus never, so far as I can find, traverses or 

 ends in the ciliary ganglion. It is, however, said to come into 

 relations with that ganglion in certain other animals. 



Dixon (No. 23) says that the ciliary ganglion, when first rec- 

 ognizable in man, is a collection of nuclei surrounding the frontal 

 nerve, that nerve, however, simply traversing the ganglion as a 

 solid and distinct bundle of fibers. The nervus trochlearis, at this 

 stage, is said to run into this same ganglion and end in it. The 

 nervus oculomotorius comes into no relations whatever with the 

 ganglion. In older embryos the ciliary ganglion is said to lose 

 entirely its early connection with the frontal nerve and the nervus 

 trochlearis, and to acquire its adult relations to the nasal nerve 

 and to the inferior division of the nervus oculomotorius. This 

 change of position, and of relation to the orbital nerves, is ac- 

 counted for by Dixon on the assumption of a migration of the 

 cells of the ganglion. He then gives an extended review of the 

 literature relating to the nerves and ganglia here concerned, going 

 over much the same ground that I did, independently of him, in 

 my work on Ainia (No. 4, pp. 535-546), but giving more atten- 

 tion to embryological considerations than to anatomical ones. His 

 work leads him to conclude : that the first formed ophthalmic 

 trunk in mammals corresponds to the nasal nerve of the adult ; 

 that the frontal nerve is developed later than the nasal, in man 

 united in a common trunk with the proximal part of the nasal 

 nerve, but in the rat arising, separately and independently, from the 

 gasserian ganglion ; that in mammals no outlying part of the 

 gasserian ganglion is present as a ganglion either for the ophthal- 

 mic or nasal nerve, in the sense of a ganglion of a posterior nerve 

 root; and that the ciliary ganglion can in no sense be the homo- 

 logue of a spinal ganglion. 



Dixon's work thus seems to me to support my conclusion (No. 

 4, p. 544) that the frontal nerve of higher vertebrates is the 

 homologue either of the portio ophthalmic profundi of Ainia, or 

 of a branch of the ophthalmicus profundus similar to the one de- 



