Many pelagic fish, e.g. carp, trout, salmon, look for their food while swimming through the well-lighted surface water. Demersal fish—flat fish, cod, haddock, etc.—seek their food by scent and touch. The cod possesses a barbel attached to its chin, by means of which it feels for its food. The Angler or Devil fish is a curious creature, from three to four feet long, and appearing to consist almost entirely of head. It has a large mouth, and teeth that are hinged so as to admit food, but prevent it from escaping. The devil fish has a long feeler on the top of its head, terminating in a tassel which, moved by the water, attracts the attention of small fish and lures them to their fate. This tassel is a sensory organ and, when it is touched by the small fish, the angler fish snaps upwards with unerring aim at a point immediately in advance of the tassel. The dog fish seeks its food exclusively by scent. If its sense of smell be destroyed, it ceases to feed spontaneously. The sole also seeks its food by smell. It is quite unable to recognize a worm by sight or touch, even when hung just above its head, but feels aimlessly over the ground seeking it by smell. =Reproduction.= Fish are male and female and, with few exceptions, reproduce their kind by laying eggs. The number of eggs laid by an individual female fish during a single spawning varies greatly, according to the species. The average number of eggs spawned by a single female fish in the course of one season, is— Ling 18,500,000 Turbot 8,600,000 Cod 4,500,000 Flounder 1,000,000 Sole 570,000 Haddock 450,000 Plaice 300,000 Herring 32,000 Shark } {A few—not more Dog fish} {than a dozen. Skate } [Illustration: FIG. 7 HERRING EGGS—×5] [Illustration: FIG. 8 PLANKTON CONTAINING FISH EGGS—×3 The large egg is that of a plaice: the smaller ones are cod and whiting. The copepod is a calanus.]