The eggs of the cod, whiting, haddock, fluke, plaice, etc., are relatively small, varying from 1/6 of an inch in the case of a halibut, to 1/25 of an inch in a flounder. The eggs are discharged into the water by the female. This process takes place gradually, and generally occupies many weeks. A few of the eggs come to maturity at a time, and are extruded. They are fertilized in the water by the spermatazoa of the male, which are discharged into the water at the same time as the eggs. The fish, both male and female, are closely crowded together on the spawning grounds, so that the fertilization of the eggs is fairly complete. With few exceptions, the eggs of most species are buoyant and float to the surface, where they drift in the warm surface water until, happily, they hatch. Unhappily, however, a very large proportion of them never reach maturity, for, either as eggs, embryos or larvae, or post larval young fishes, they soon fall a prey to marauding fish. It is estimated that, of the thirty-two thousand eggs laid annually by each female herring, not more than two reach maturity. The spawning grounds of the herring are not definitely known. Research is being carried out at present with a view to solving this question. Haddock are to be caught in various likely parts of the sea, marked with the place of capture, and their interiors examined for herring spawn. Certain demersal fish, notably shark, dog fish and skate, deposit a few large, demersal eggs—about a dozen in the year—in a carefully selected spot. The incubation period of these eggs is unusually long, being from six months to over a year, according to the species and the temperature of the water. Parental care is exhibited by very few fishes in this part of the world, although many foreign fish build nests and care for their young, often carrying them in their mouths. Certain kinds of dog fish and angel fish keep their young inside their oviducts until they are completely formed. The only notable example of a fish common to British waters that exercises parental care is the stickleback. Spawn is deposited by a number of different females in a nest constructed of stones and weed, and is guarded by a male until all the eggs are hatched. The eggs of the crustacea, for example the lobster, are found attached in large numbers to the swimmerets—feathery processes that are situated underneath the tail. When in this condition, the lobster is known as “berried,” and, if captured, should be returned to the sea. The eggs are sticky and are laid while the lobster lies on her back, and so become attached to the hairs of these feathery processes. Berried crabs, prawns and shrimps may also be observed on the seashore in the spring and early summer.