CEPHALOPODA 



523 



into the funnel and then on to one of the tentacles (the hectocotylus) 

 which is modified for the purpose of transferring the sperm to the 

 female. In Sepia, the modification shows itself only by the suppres- 

 sion of some rows of suckers at the base of the tentacle, but in other 

 forms it is profoundly modified. In Octopus, the end of the tentacle 



pig.ep. 



op.n. 



Fig. 384. Eyes of Mollusca. A, Nautilus. B, Helix. C, Sepia. D, Pecten 

 (inverted type), cil.m. ciliary muscle; cor. cornea; d.ret. distal and pr.ret. 

 proximal layers of the double retina of Pecten ; ir. iris ; /. lens ; Id. eyelids ; 

 op.g., op.n. optic ganglion and nerve ; pig.ep. pigmented epithelium ; ret. retina ; 

 tap. tapetum ; vit.h. vitreous humour. In Sepia the cartilage is shown in black. 



is spoon-shaped and the tentacle is extended so as to enter the 

 mantle cavity of the female. In other octopods, a cyst is formed at 

 the end of the tentacle in which the spermatophores are stored ; from 

 it a long filament is protruded. 



Other Dibranchiata. The members of this group are classified in 



