OUR BEST FEATURES 



simple eye of Nautilus (Plate, 1924, pp. 474-478). 

 The retina and indeed the whole eye of cephalopods 

 develops in the embryo as a pouch in the skin, and 

 is thus comparable only to the lens of vertebrates; 

 in the latter the retina is developed from the optic 



cor-' 



COr^ 



Fig. 95. Development of the Eye in Cephalopod Molluscs. 



(After Plate.) 



(From Allgem. ZooL, Gustav Fischer.) 



For details, see p. xxxvi. 



cup, which is an outgrowth of the brain. Thus 



at every important anatomical point the paired 



eyes of cephalopods and of vetebrates differ 



profoundly from each other. From all this it is 



evident that the paired eyes of cephalopods and 



of vertebrates are not homologous with each other 



at all, that they have arisen from dissimilar 



beginnings and have come to resemble each other 



181 



