CEPHALOPODS. 
3 2 9 
occur in all seas. Variations in colour, the relative length of the arms, the size 
of the suckers, and the character of the hectocotylised or modified arm of the male, 
are among the distinguishing features of the species. Although we usually speak 
of the octopods as shell-less or naked molluscs, an indication of an internal shell 
is present, in the form of two short styles, embedded in the tissues of the mantle. 
These molluscs are solitary creatures when adult, but they are said to herd together 
COMMON OCTOPUS. 
in small companies when young. They live in the fissures of rocks, or hide away 
beneath great boulders. When they walk or creep, they elevate the sack-like 
body above the head, and progress slowly upon the extremities of the arms, which 
are a little curved near the tip. They can creep in any direction, but they prefer 
a side-way movement. On the contrary, if their progress in walking is com¬ 
paratively slow, this is compensated by the rapidity of their movements when 
swimming. Body foremost, with the arms stretched beyond the head, they dart 
