422 MANUAL OF ZOOLOGY. 



The organs of sense are a pair of large and very highly devel- 

 oped eyes, and a pair of auditory sacs. The great oesophageal 

 nerve collar is protected by a cartilaginous plate, which fore- 



Fig. 226. Central organs of the circulation, gills, and renal organs of Sepia officinalis. 

 (After John Hunter), a Aorta ; v Vena cava ; v' i>' Visceral veins ; c Systemic 

 heart ; d d Dilatations of branchial veins on entering the heart ; e e Branchial 

 hearts ; b b Branchiae ; r r Renal organs. 



shadows the cranium of the Vertebrata ; this also sends out 

 prolongations which strengthen and defend the eye, and the 

 auditory chambers are excavated in its substance. 



The sexes in all the Cephalopoda are in different individuals, 

 the males and females generally being more or less unlike 

 externally. In this order the ducts of the generative organs 

 open into the pallial chamber, and each individual, besides the 

 essential organs of reproduction (testis or ovary), generally 

 possesses an accessory gland ; that of the female secreting a 

 viscid material which unites the eggs together, whilst that of 

 the male coats the spermatozoa, and aggregates them into 

 peculiar worm-like filaments, from six to eight lines in length, 

 termed " spermatophores," or the "moving filaments of Need- 

 ham." The spermatophore is filled with spermatozoa, and 

 possesses the power of expanding when moistened, rupturing, 

 and expelling the contained spermatozoa with considerable 



