274 THE WORLD OF THE SEA. 
which operate with three strong, cartilaginous jaws, producing that 
d 
peculiar bite called “the leech-bite ;” but, in the place of these 
lancet-jaws, we find three slender tentacles. But how can these 
pierce the skin of the fish? The leech does not cut the skin, 
and probably the tentacles are only organs of feeling, by means 
of which the parasite fixes upon the proper place to make his 
attack. Having fixed his sucker, he exhausts the air so completely, 
that the skin of the fish bursts at the place where the suction is 
applied. Hence the marine leech tears the skin; the fresh-water 
THE SPINY ALBIONE, BRANCHELLION. 
(Albione muricata.) (B. Torpedinis.) 
leech cuts it. It would seem that the tubercles which roughen 
the body are intended to keep the leech from being rubbed too 
violently against the skin of the fish to which it is attached. 
The annelids must often stand in need of this defence, for it cannot 
be expected that the skate or the torpedo will passively submit to 
be continually preyed upon. During the day-time, these annelids, 
like the rest of their kind, lie quiet and still; night with them 
is the time for action, when they awake from their apathetic state, 
and vigorously suck their unfortunate victim. 
The sea-leeches prefer red blood, and therefore always attack 
fish—never mollusks. They usually choose some member of the 
ray family, and generally flat fish, probably because their skin is 
less cartilaginous, and perhaps, also, because these fish live either 
upon or very near the bottom—a circumstance peculiarly favour- 
able to the necessities of these sanguinary annelids. It is remark- 
