Eycleshymer- Davis, Epiphysis and' Paraphysis in Amia. 63 



rudimentary eyes another question arises, viz : Is there suffici- 

 ent evidence to show that two of these unite to form the pineal 

 outgrowth ? 



Concerning the fate of the anterior pair we read the follow- 

 ing in Prof. Locy's earher paper {Anat. Anz., 1893, p. 173) : 



" I have been able to follow the anterior pair, step by step 

 through a graded series of embryos, without having once lost 

 trace of them, and to see that they enter the thalamencephalon 

 and give rise to the pineal outgrowth. The posterior pair, 

 which are smaller, are not to be followed in this definite way, 

 they become fainter and, I believe, they fade away." 



Further, p. 174. " The accessory optic vesicles may, from 

 certain marks that remain fairly constant, be identified with 

 certainty both at this stage, and in later stages" * * "The 

 auditory vesicle, in the process of sinking below the surface, 

 is shifted backwards, and finally, there comes to be five of 

 these elevations in front of it (Fig. 5 n^ to n^*^) and, also, in 

 the meantime, mid-brain and cerebellum have appeared. But 

 all these transformations go so clearly that no confusion need 

 arise if one has a suitable series of embryos." 



In the final paper certain statements are found which lead 

 one to infer that the fate of even the first pair of vesicles may 

 perhaps be regarded as somewhat problematic, viz : 



"The bulging of the walls to form the mid-brain vesicle 

 has come on insiduously, and has taken a position behind the 

 vesicles of the paired eyes, in apparently the same position pre- 

 viously occupied by the accessory vesicles. These transforma- 

 tions are confusing, as the walls of the mid-brain resemble the 

 accessory optic vesicles grown larger. In an earlier published 

 paper I made the mistake of identifying the mid-brain with the 

 accessory optic vesicles ; but it was merely an error of identifi- 

 cation, and did not effect the main contention of that article." 



In the former paper p. 178, the author states : — "We have 

 two pairs of these embryonic organs, in addition to the lateral 

 eyes, and we have thus actually present, in this animal the ma- 

 terial to supply two distinct outgrowths both visual in charac- 



