THE CEPHALOPODA 325 
devoid of chromatophores. Eventually the membrane of the 
cyst bursts and remains attached to the dorsal surface of the arm, 
forming the spermatophore sac. The uncoiled arm is pedunculated, 
that is to say, is attenuated towards its base, and it bears at its 
extremity a little pouch (Fig. 287, «) containing a long filament, 
which is extended prior to the act of fertilisation (Fig. 287, y). The 
spermatophore sac communicates with a canal in the interior of the 
arm, and this canal is continued into the terminal filament and 
opens by an orifice at its free extremity. The hectocotylus when 
detached is able to live and move about for a considerable time, 
until finally it penetrates into the pallial cavity of a female and 
fixes itself in the neighbourhood of the genital aperture. In those 
Dibranchia in which the hectocotylus is not autotomous the 
hectocotylised arm (or arms) is inserted into the pallial cavity of 
the female (Fig. 288, 3) in such wise as to deposit the spermato- 
phores in the terminal portion of the oviduct in Octopus, or to fix 
Fig. 288. 
Copulationiof Octopus. A, the female; B, the male. fw, funnel of the female ; 3, third right 
hectocotylised arm of the male. (After Racovitza.) 
them in the neighbourhood of the oviducal orifice in Fossia and 
Sepiola. In Sepia and Loligo the spermatophores are simply deposited 
on the ventral lobes of the buccal membrane, and in Nautilus they 
are deposited on the folded lamellae on the ventral side of the 
buccal orifice (Fig. 255, m). 
The eggs are laid shortly after copulation. In Nautilus they are 
laid singly, each egg being about four centimetres long and surrounded 
by two thick shells, the outermost of which is partly open (Willey). 
In the Dibranchia the eggs are aggregated together, but in the 
Octopoda and in Sepia, Sepiola, and Rossia each egg has a separate 
envelope, whereas they are united to form longer or shorter gela- 
tinous strings, which are joined together and fixed by one extremity 
in Loligo, but are single and floating in the pelagic Oigopsida. In 
Eledone only about sixty eggs are laid at one time, in Octopus more 
than a hundred, and some species of Loligo lay more than 40,000 
eggs. Some Octopods are incubatory: the female Argonauta, for 
example, protects the eggs in the shell peculiar to her sex. 
