200 RAMUS OPHTHALMICUS SUPERFICIALIS. 



their obliqueness), and runs parallel and dorsal to the ophthalmic 

 branch of the fifth nerve, and may easily be seen in this posi- 

 tion in longitudinal sections belonging to stage O ; but its 

 changes after this stage have hitherto baffled me, and its final 

 fate is therefore, to a certain extent, a matter of speculation. 



The two other branches of the seventh, viz., the hyoid or 

 main branch and mandibular branch, retain their primitive 

 arrangement till the clos€ of stage O. 



The fate of the remarkable anterior branch of the seventh 

 nerve is one of the most interesting points v^hich has started 

 up in the course of my investigations on the development of 

 the cranial nerves, and it is a matter of very great regret to 

 me that I have not been able to clear up for certain its later 

 history. 



Its primitive distribution leads to the supposition that it 

 becomes the nerve known in the adult as the ramus ophthahnicus 

 superficialis of the fifth nerve, and this is the view which I 

 admit myself to be inclined to adopt. There are several 

 points in the anatomy of this nerve in the adult which tell in 

 favour of accepting this view with reference to it. In the first 

 place, the ramus ophthalmicus superficialis rises from the brain 

 (vide description above, p. 194), quite independently of the 

 ramus ophthalmicus profundus, and not in very close con- 

 nection with the other branches of the fifth, and also con- 

 siderably behind these, quite as far back indeed as the ventral 

 root of the seventh. There is therefore nothing in the position 

 of its root opposed to its being regarded as a branch of the 

 seventh nerve. Secondly, its distribution, which might at first 

 sight be regarded as peculiar, presents no very strange features 

 if it is looked on as a ramus dorsalis of the seventh, whose 

 apparent anterior instead of dorsal course is due to the cranial 

 flexure. If, however, the distribution of the ramus ophthal- 

 micus superficialis is used as an argument against my view, 

 a satisfactory reply is to be found in the fact that a branch 

 of the seventh nerve certainly has the distribution in question 

 i/n the embryo, and that there is no reason why it should 

 not retain it in the adult 



Finally, the junction of the two rami ophthalmici, most 

 remarkable if they are branches of a single nerve, would present 



