14 
SEA MONSTERS UNMASKED, 
means of the communication between the ink-bag and the 
locomotor tube, it happens that when the ink is ejected, 
a stream of water is forcibly emitted with it, and thus the 
very effort for escape serves the double purpose of pro- 
pelling the creature away from danger, and discolouring 
the water in which it moves. Oppian has well described 
this — 
" The endangered cuttle thus evades his fears, 
And native hoards of fluids safely wears. 
A pitchy ink pecuhar glands supply 
Whose shades the sharpest beam of light defy. 
Pursued, he bids the sable fountains flow, 
And, wrapt in clouds, eludes the impending foe. 
The fish retreats unseen, while self-born night 
With pious shade befriends her parent's flight." 
Professor Owen has remarked that the ejection of the 
ink of the cephalopods serves by its colour as a means of 
defence, as corresponding secretions in some of the mam- 
malia by their odour. 
It is worthy of notice that the pearly nautilus and the 
allied fossil forms are without this means of concealment, 
which their strong external shells render unnecessary for 
their protection. 
From the sac-like body containing the various organs, 
protrudes a head, globose in shape, and containing a brain, 
and furnished with a pair of strong, horny mandibles, which 
bite vertically, like the beak of a parrot. By these the 
flesh of prey is torn and partly masticated, and within 
them lies the tongue, covered with recui-\^ed and retrac- 
tile teeth, like that of its distant relatives, the whelk, 
limpet, &c., by which the food is conducted to the gullet. 
Around this head is, as I have said, the organ which is 
equivalent to the foot in other molluscs — that by wiiich 
the slug and the snail crawl — only that the head is 
