488 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
the male, are stored in this arm, which, when packed with 
them, becomes detached and in some way enters the mantle 
cavity of the female. The arm of Hledone, however, is 
less specialised and not autotomous, and the chief 
modification is at the tip, as in Octopus. Probably then 
the tip of this arm is inserted in the terminal part of the 
oviduct of the female, after the manner actually watched 
and figured by Racovitza in the case of Octopus. ‘The 
hectocotylised arm of Hledone is somewhat shorter than 
the others—about 15 mm. less m the small specimen 
examined of . aldrovandi. Examining the ventral sur- 
. face, it may be seen that the third right arm—counting 
ventrally from the dorsal pair—bears a groove on its 
ventral aspect (IV, g7.). This is formed by a narrow fold 
of skin, and runs from the base to the tip of the arm, 
where the groove is enlarged to form an oval depression 
on the oral surface of the arm tip (IV, depr.). Moreover, 
the other seven arms of the genus Hledone are somewhat 
modified in the male. The suckers at the tip are set more 
closely together than in the female, and are shallower 
(IV b, S). The sixth and seventh suckers from the tip 
have practically no cavity at all, and the remaining ones 
are represented by tiny flat pads (IV 6, P). 
(B) Visceral dome.—'This is the name given to the 
mass formed by the principal viscera of the body. 
Hixternally it is enclosed by the thick muscular manile. 
It 1s oval in shape, being longer than it is broad, and 
bluntly rounded posteriorly. Anteriorly the visceral 
dome is marked off from the head by a slight constriction 
or neck. The dorsal surface is more convex than the 
ventral, and lies uppermost during creeping and 
swimming. As the shell is greatly reduced in -Eledone, 
the visceral dome is unprotected save oy the skin and 
muscular mantle. 
