212 Journal OF Comparative Neurology. 



The superior ramus at once becomes applied to the mesial 

 side of the m. rectus superior, and is distributed to this muscle 

 without coming in contact at any point with the trigeminal 

 twig mentioned in Case A. 



The inferior ramus passes dorsally of the m. rectus internus 

 in two divisions. These divisions unite, however, before they 

 come in contact with any muscle and before they give off any 

 branches. On the dorsal surface of the m. rectus inferior the 

 nerve comes in contact with the mesial surface of the inferior 

 ciliary nerve and at this point'of contact there are few ganglion 

 cells. The ciliary nerve is clearly distinguishable from the 

 oculomotor and passes laterad across the dorsal surface of the 

 muscle while the third nerve comes to lie on the mesial side of 

 the muscle. The branches which supply the m. rectus internus 

 and m. obliquus inferior arise proximally of the contact with 

 the m. rectus inferior and the branch to the latter muscle passes 

 cephalad laterally of the m. levator bulbi. 



Case C. — The inferior ramus passes ventrally of the m. 

 rectus internus and becomes applied to the ventro-mesial aspect 

 of the m. rectus inferior. From this position it sends fibers 

 back to the ventral side of the m. rectus internus and, later, it 

 gives off the branch to the m. obliquus inferior. 



These three cases show the following essential relation of 

 the third nerve in Amblystoma : (a) The m, rectus superior is 

 innervated by the superior ramus, which passes dorsally of the 

 r. ophthalmicus profundus. That the nerve ever anastomoses 

 with a trigeminal twig with which it sometimes comes in con- 

 tact is made entirely improbable by Case B where no such con- 

 tact occurs. (b) The mm. rectus inferior, rectus internus and 

 obliquus inferior are innervated by the inferior branch which 

 passes ventrally of the r. ophthalmicus profundus. 



The order of branching in Case B renders it wholly im- 

 probable that the rectus internus and obliquus inferior receive 

 fibers from the fifth nerve, as would seem possible from Case A 

 taken alone. Observations in Case B, and on other specimens 

 also, make it improbable that this trigeminal nerve, with which 

 the third sometimes comes in contact, has anything to do with 



