310 LL use A. 



of tlio pericardium around the systemic and brancl]ial hearts and tlie thin- 

 wallt'd genital sac, one wall of whicli Vjears the genital ducts, while on the 

 other the sexual cells arise or the ducts of a separate sexual gland oiien 

 (fig. 392). 



The gonads of the always dioecious CeiAalopoda are unpaired 

 and lie far back in the visceral sac. The ducts in the female 

 Octopoda (rarely in the males) and in some Decapoda (Oic{opsida) 

 are paired. In Nautilus only the right duct is . functional in 

 either sex, although the left is well developed. Elsewhere there 

 is only the left duct. The oviducts are saccular with glandular 

 walls; independently of them two pairs of glands open to the 

 exterior, the accessory glands and the large nidamental glands. 

 The vas deferens (fig. 302) is more complicated. It has swellings 

 known as seminal vesicle, prostate, and Needham's sac, in which 

 tlie spermatophores are stored. These have such a complicated 



Fig. :(93.— Spermatophore of Sepia. (From Hatschek, after ]\Iilne Edwards.) (f, dis- 

 charging apparatus ; 6, pacliet of spermatozoa ; r, envelope. 



structure and show such motions when swollen with water that 

 they were long regarded as piarasitic worms (fig. 393). 



Fir.. .'iM.— Male of Argonanfa nrgn. (After MiiUcr, from Hatschek.) l-i, arms of right 

 side ; l.-U., arms of left side ; .;, Iiectocotylisi'd arm. at the left in its sac, at the 

 i-ight protruded. 



'i'lu! spermatophores are conveyed to the female by means of 

 more or loss modified (hectocotylised) arms of the male. In a few 

 genera tlie proper tentacle becomes a ' llectocotylus " (fio-. 394). 



