MORPHOLOGY OF ANIMALS 



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Fig. 28. Types of Eyes. A, Eye of Haliotis (Mollusk) of "pin-hole camera" type ; e, 

 epidermis; cv, cavity of eye; R, retina of direct type; A^, optic nerve. (After Hatschek). B. 

 Pineal (unpaired) eye of a lizard (Hatteria) ; i, integument ; c, connective tissue capsule ; /, 

 lens; r, retina; n, nerve. (After Parker and Haswell). C and D, Diagrams of two stages in 

 formation of paired eyes of vertebrates. C, evagination of optic vesicles from fore-brain. 

 D, invagination of epidermis into optic vesicles to form lens, /, and infolding of retina, r, 

 which thus becomes inverse. (After Boveri). 



the retinal cells are turned toward the cavity of the vesicle, 

 while the opposite ends, which are directed away from the 

 vesicle, are prolonged into fibres; such an eye has a direct 

 retina. This type of eye reaches its highest development 

 among the cephalopods, where it bears a striking 



e, though 



