58 



Journal of Comparative Neurology. 



have shown him. Secondly had he carefully examined the eye 

 muscles of his Amphiuma he would have found that all are 

 present, while the Sarasins say that the retractor muscle of the 

 tentacle is probably produced from the retractor bulbi. 



Figure J. Portion of section through the head of a larval Amphiuma ; let- 

 ters as before exceptingy, frontal bone ; /, parietal bone; ni, ramus nasalis in- 

 ternus of ophth. profunc) us ; osp, orbitosphenoid ; ir, trabecula ; ps, parasphenoid; 

 0, optic nerve; w, maxillary bone ; b, blood vessel ; b'* and nix"*, blood vessel and 

 branch of maxillary nerve constituting the tentacular apparatus of Davison. 



On the other hand I find a canal and a solid structure lying 

 immediately beneath it, in the very place where Mr. Davison's 

 tentacular apparatus appears, but I interpret the features differ- 

 ently. The supposed degenerate muscle is a peripheral branch 

 of the maxillary nerve, the tentacular canal is one of the branches 

 of the sub-orbital blood vessels. The only objection to this is 

 that our author describes the canal as lined by columnar 

 epithelium, a condition possibly the result of contraction of the 

 vessel and a consequent throwing of its intima into folds, or 

 possibly he has mistaken the contained blood corpuscles for 

 epithelial cells. The short course which he allows the canal is 

 explained by the fact that distally it breaks up while more 

 proximally it is compressed as it passes between two nerve 

 twigs. 



