166 
NOTES AND MEMORANDA. 
Aphia pellucida, Day (Latrunculus pellucidus, Collett)—An adult 
male of this species, 24 inches long, was taken in the tow-net at the 
surface south of the Mewstone on June 12th last. When alive it 
was very transparent, with a few scattered black chromatophores 
along the back and the ventral edge. 
Specialised Organs seen in Action—As we often can only conjecture 
the exact function of special organs in marine animals, and oppor- 
tunity seldom occurs to see them in actual operation, the following 
observations are perhaps worth recording. 
It is well known that the decapod Cephalopoda have, in addition 
to eight short arms, two others which are long, provided with suckers 
only on the enlarged terminal portions, and usually retracted into 
sockets. A specimen of Sepia has for some months past been living 
in a healthy and vigorous condition in one of the aquarium tanks, 
At first it injured the posterior end of its body by knocking against 
the sides of the tank, but having got accustomed to confinement it 
ceased to do this and the abrasion began to heal up. It was found 
to catch and devour small crabs with eagerness. In catching this 
kind of prey it threw itself upon the crab with its short arms spread 
out, and although the tentacular arms were seen to be protruded 
this was done so rapidly that the movement could scarcely be 
followed. When a prawn was offered to the creature much more 
use was made of the tentacular arms. The prawn moves very slowly 
and deliberately until alarmed, and then darts away with great 
rapidity by flapping its tail. It also has the habit of retreating into 
crevices between the rocks when an attempt is made to catch it. 
The cuttle-fish accordingly stalks a prawn carefully, to avoid 
alarming it, becoming at the same time evidently keenly excited, its 
colour deepening in places and constantly changing, blushing as it 
were all colours at once. When it gets within a few inches of the 
prawn it raises its two upper arms and looks like an elephant with 
uplifted trunk, and then suddenly darts out its two tentacular arms 
together, seizes the prawn between the clubbed ends, and imme- 
diately draws it back within reach of the short arms which close 
over it and hold it firmly while it is devoured. The stroke of 
