CRITIQUE OF THE EYE-MUSCLE NERVES. 235 



optic chiasma." In Menidia, too, the branches do not 

 leave the oculomotorius in the same order as in Amia, 

 or any other form figured by Allis, the nerve for the m. 

 obliquus inferior being the first instead of the last branch 

 to be given off. This nerve passes under the inferior and 

 internal recti, as in Allis' figures, but the main nerve, 

 viz., the portion for the ciliary ganglion and for the in- 

 ferior and internal recti, lies above these muscles. Allis' 

 conjecture that the arrangement in Amia is typical for all 

 ganoids and teleosts certainly will not hold, so far as the 

 teleosts are concerned, at any rate. 



Allis points out certain errors and ambiguities (due in 

 part to misplaced reference letters) in my account of the 

 eye-muscles in Amblystoma ('94). I have re-examined 

 these nerves and the correct relations in Amblystoma are 

 as follows (cf. Fig. 14) : 



The IV and VI nerve require no additional comment 

 save that they conform to Allis' diagram of the Anura and 

 not to his diagram of the Urodela. 



The foramen of the III nerve is a little caudad and very 

 slightly dorsad of that of the optic nerve. Immediately 

 after its exit from the foramen the oculomotorius lies just 

 laterally of the emerging optic nerve and mesally of the 

 mm. recti superior, inferior and internus, near their 

 tendinous origins. Just laterally of these muscles is the 

 r. ophthalmicus V, all of these structures lying at very 

 nearly the same dorso-ventral level. Here the III nerve 

 divides into its dorsal and ventral rami, the former pass- 

 ing to the m. rectus superior only. This branch and its 

 muscle lie dorsally of the ophthalmic nerve and the latter 

 crosses the n. opticus dorsally. 



The ventral branch of the III nerve turns down behind 

 the optic nerve and crosses the latter on its ventral side, 

 turning laterally and crossing over the m. rectus internus 

 very near its tendinous origin. Here it lies crowded 

 closely between the rectus internus and the dorsal edge of 

 the rectus inferior, the former lying mesally, the latter 

 laterally of it. In some cases a few fibres seem to enter 

 the rectus internus at this point. It then enters the 



