448 Avery E. Lambert. 



Schimkewitsch's paper deals accurately with the general mor- 

 phology of the eyes, but fails to relate them properly with the optic 

 ganglia. His statement that the optic nerves are derived from the 

 cephalic ganglia is somewhat ambiguous, although he probably refers 

 to the procephalic lobes. 



One of the most important works relating to the subject is the 

 paper by Loey on the development of A galena luvvia. Although he 

 failed to understand the significance of the fold which forms the roof 

 of what he calls the "optic vesicle" (the cerebral vesicle), he was 

 the first to correctly describe the morphology of the anterior median 

 eyes. 



His conclusions concerning the mode of origin of the posterior 

 median, and lateral, eyes need revision, as has l)een pointed out by 

 Kishinouye. Locy holds that the accessory eyes arise in association 

 with ectodermal infoldiiigs in a way somewhat similar to that in 

 which the principal eyes are formed. The ectodermal invaginations 

 with which the lateral eyes are associated in their formation, how- 

 ever, enter into the fonnation of the optic lobes, and form the point 

 of origin from which the optic nerA'es, supplying the lateral eyes, 

 arise. They do not, themselves, give rise to the eyes. 



He calls attention to a very important point, that is, the inversion 

 of the retinal elements which is brought about by the infolding of the 

 optic fold, thus explaining how it occurs that "the way in which the 

 light traverses the median anterior eyes of spiders is similar to the 

 method by which light reaches the percipient elements in the retina 

 of the vertebrate eye." 



Another important paper which deals with the subject is that by 

 Kishinouye. He recognizes the fact that the elements which enter 

 into the formation of the anterior median eyes are originally located 

 on the posterior margins of the covering of the cerebral vesicle; but 

 he fails to note that these optic elements are brought into this posi- 

 tion from thp lateral margins of the cephalic plate. He finds, foUoAV- 

 ing Locy, that the inversion of the retinal elements of the median 

 eyes is due to the "processes by which the eyes are formed." 



Kishinouye also states concerning the origin of the optic nerves, 

 that they arise as elongations of the retinal cells, forming fillers which 



