4So 



MANUAL OF ZOOLOGY 



(Fig. 289, c. />) 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. I) are thereby pressed outwards so 

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



rci scZ 



ch scl P l 



rl 



pet 



Fig. 290. — 1 he eye. A, m sagittal section; B, the entire organ, external aspect; 

 en, cornea; e/i, choroid; el. pr, ciliary processes; ir, iris; /, lens; opt. nv 

 optic nerve; pet, pecten ; rt, retina; scl, sclerotic; scl. 41. 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 



