THE CEPHALOPODA. 451 



given off from these ganglia are those which go to the bran- 

 chiae. 



Eyes, olfactory organs, and auditory sacs, are always 

 present. The eyes of the Cephalopoda may be lodged in 

 orbital cavities at the sides of the head, as in all the Dibran- 

 chiata ; or may be pedunculated, as in Nautilus. In the 

 former case, the eye is inclosed partly by the cephalic car- 



M 



Fig. 128.— Sepia officinalis.— The nervous mass which surround? the gullet ; JV, the 

 cerebral ; iV', the pedal ; N", the parieto-splanchnic ganglion ; ao, the aorta ; oe, 

 the oesophagus ; o f . buccal nerves ; P f s nerves to the anus ; M, pallial nerves ; g, 

 superior; g', inferior buccal ganglion. (After Garner.) a 



tilage, to which sometimes special orbital cartilages are add- 

 ed, and partly by a fibrous capsule continuous with these. 

 The fibrous capsule becomes transparent over the eye, and 

 gives rise to what is variously interpreted as the representa- 

 tive of the cornea, or as that of the eyelids of vertebrated ani- 

 mals. This transparent coat is sometimes entire, or presents 

 only a small perforation ( Octopus, /Sepia, Loligo, and the 

 other Myopsidm of D'Orbigny) ; sometimes it has a wide 

 opening, through which the crystalline lens may project (Lo- 

 ligophes, Ommastrepsis, and the other Oigopsidce of D'Or- 

 bigny) ; and sometimes it is altogether absent, and the capsule 

 of the eye becomes an open cup (Nautilus). 



In the Dibranchiata? a great part of the chamber of the 

 capsule of the eye is occupied by the ganglion, into which the 

 optic nerve enlarges after entering it ; by muscles ; and by a 

 peculiar white glandular substance. Lining the capsule, but 



i "Trans. Linnsean Society," 1836. 



2 See Hensen, " Ueber das Auge einiger Ccphalopoden." (Zeitschrift fur 

 ivissenschaftliche Zoologie, 1865.) 



