4 8o 



MANUAL OF ZOOLOGY 



SECT. 



(Fig. 289, c. b) is of great size, and has a large median portion 

 and two small lateral lobes or flocculi (/) ; the surface of 

 the middle lobe is marked by grooves passing inwards in a 

 radiating manner and carrying with them the grey matter, 

 the extent of which is thus greatly increased. The hemi- 

 spheres (c. h) extend backwards to meet the cerebellum, 

 and the optic lobes (o. /) are thereby pressed outwards so 

 as to take up a lateral instead of the usual dorsal position. 



en 



Phe eye. A, in sagittal section; B, the entire organ, external aspect; 

 :a; ch, choroid; cl. pr, ciliary processes; z'r, iris; /, lens; opt. nv, 



FIG. 290 The 

 en, cornea 



optic nerve; pet, pecten; r't, retina; " scl, sclerotic; scl. pi, sclerotic plates! 

 (After Vogt and Yung.) 



The eye (Fig. 290) is not even approximately globular, 

 but has the form of a biconvex lens. Sclerotic plates 

 are present, and there is a large pecten in the form of a 

 plaited and strongly pigmented membrane projecting into 



