MOLLUSC A 



The spermatophores are complex structures about 2 cm. 

 long, they have a receptacle in which the minute spermatozoa 

 are stored up, and a long tightly-coiled spiral thread, the ex- 

 pansion of which explodes the capsule, and the spermatozoa 

 rush out. 



In the female the ovary occupies the same position as the 

 testis in the male ; the cavity of both these generative glands 

 communicates with the pericardial portion of the coelom, 

 though partly shut off from it by a septum. A cushion 

 projects into the lumen of the ovary, which bears ova in various 

 stages of developement ; from the ovary the oviduct, which is 

 ciliated, passes to its external opening to the left of the anus. 

 Accessory glands are present ; of these the most important are 

 a large pair of nidamental glands, which deposit the substance 

 of the egg capsules ; in Sifia there is a second smaller pair of 



Fig. 129. — a, Male of Argonauta argo, with the hectocotylised arm still contained 

 in its enveloping cyst, four times enlarged (after H. Miiller). h, Hectocotylus of 

 Tremoctopus violaceus (after Kblliker). 



nidamental glands, as well as the large ones. The egg capsule 

 is prolonged into a stalk, by means of which the eggs are kept 

 together, and the collection of eggs somewhat resembles a cluster 

 of grapes. 



In Sepia one of the arms in the male is slightly modified, 

 and probably assists, in the deposition of the spermatozoa, but in 



