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 ending in long tendrils, and useful for attaching them to corallines or seaweeds on the bed of the ocean. But it is worth noticing that in colour the egg-cases closely resemble the common wrack to which they are oftenest fastened; and as they wave up and down in the water with the dark mass around them, they must be almost indistinguishable from the wrack itself by the keenest-sighted of their enemies. This protective resemblance, coupled with the toughness and slipperiness of their leathery envelope or egg-shell, renders them almost perfectly secure from all evil-minded intruders. As a consequence, the dog-fish lay but very few eggs each season, and those few, large and well provided with nutriment for their spotted offspring. It is these purses, and those of the thornback and the edible skate, that we oftenest pick up on the English coast. The larger oceanic sharks are mostly viviparous.