EYE OF THE OCTOPUS. 



165 



there is no chamber before the crystalline lens filled 

 with aqueous humour ; the lens is of short focus, and, 

 instead of being simply convex on each side, it is di- 

 vided into a sort of double lens^ or into two portions, 

 (the anterior being the smallest,) by a circular furrow, 

 into which is fixed the post-pigmental retina with its 

 anterior lining of pigment. The globe of the eye is 

 covered with an outer coat, which is tough and fibrous, 

 and may be regarded as the sclerotic. The diagram 



Eye of the Octopus. 



a, a, the crystalline lens ; b, the transparent skin supplying the place of the 

 cornea; c, the channber containing the vitreous humour; d, d, the black pig- 

 ment; e, the post-pigmental retina, expanded from/, the optic ganglion ; g, 

 the pre-pigmental retina; h, h, the sclerotic, or external tunic of the globe of 

 the eye. 



