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 JJlbran- 

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

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



Fra. i2%.— Sepia offlcimlis.— The nervous mass which surround? the gullet ; N^, the 

 cerebral; ^^ the pedal ; A^'', the parieio-splanchuic gauL'lion ; «o, the aorta; o?, 

 the cesophagus; (/. buccal narves ; P\ ueive.i to the anus; J/, palliai nerves; g, 

 superior; g^, inferior buccal ganglion. (After Gainer.) ^ 



tilage, to wdiich sometimes special orbital cartilages are add- 

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

 The fibrous capsule becomes transparent over the eve, and 

 gives rise to what is variously interpreted as the representa- 

 tive of the cornea, or as that of tbe 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, tlirough which the crystalline lens may project {TjO- 

 li'jophes, Ommastrepsis, and the other Oigopsidm of D'Or- 

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

 of the eye becomes an open cup {Nautilus). 



In the Dihranehiata^ a great part of the chamber of the 

 capside 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 



1 "Trans. Linnsean Society," 1830. 



2 See Ilensen, " Ueber das Auge einiger Ceplialopoden." {Zeitschrift fur 

 ivisseiischaftliche Zoologie^ 1865.) 



