rine lamprey, the hag
or borer, so called because it lives parasitically upon other fishes,
whose bodies it enters, and then slowly eats them up from within
outward, till nothing at all is left of them but skin, scales, and
skeleton. They are repulsive eel-shaped creatures, blind, soft, and
slimy; their mouth consists of a hideous rasping sucker; and they pour
out from the glands on their sides a copious mucus, which makes them as
disagreeable to handle as they are unsightly to look at. Mackerel and
cod are the hag's principal victims; but often the fisherman draws up a
hag-eaten haddock on the end of his line, of which not a wrack remains
but the hollow shell or bare outer simulacrum. As many as twenty of
these disgusting parasites have sometimes been found within the body of
a single cod-fish.

Yet see how carefully nature provides nevertheless for the due
reproduction of even her most loathsome and revolting creations. The
hag not only lays a small number of comparatively large and well-stored
eggs, but also arranges for their success in life by supplying each
with a bundle of threads at either end, every such thread terminating
at last in a triple hook, like those with which we are so familiar in
the case of adhesive fruits and seeds, like burrs or cleavers. By means
of these barbed processes, the eggs attach themselves to living fishes;
and the young borer, as soon as he emerges from his horny covering,
makes his way at once into the body of his unconscious host, whom he
proceeds by slow degrees to devour alive with relentless industry, from
the intestines outward. This beautiful provision of nature enables the
infant hag to start in life at once in very snug quarters upon a
ready-made fish preserve. I understand, however, that cod-fish
philosophers, actuated by purely personal and selfish conceptions of
utility, refuse to admit the beauty or beneficence of this most
satisfactory arrangement for the borer species.

Probably the best known of all fishes' eggs, however (with the solitary
exception of the sturgeon's, commonly observed between brown bread and
butter, under the name of caviare), are the queer leathery purse-shaped
ova of the sharks, rays, skates, and dog-fishes. Everybody has picked
them up on the seashore, where children know them as devil's purses and
devil's wheelbarrows. Most of these queer eggs are oblong and
quadrangular, with the four corners produced into a sort of handles or
streamers, often