1. Mackerel, geographically speaking, are distributed over a wide expanse of water, embracing the whole of the European coasts, as well as the coasts of North America, and this fish may be caught as far southward as the Canary Islands. 2. The mackerel is a wandering unsteady fish, supposed to be migratory, but individuals are always found in the British seas. 3. This fish appears off the British coasts in quantity early in the year; that is, in January and February. 4. The male kind are supposed to be more numerous than the female. 5. The early appearance of this fish is not dependent on the weather. 6. The mackerel, like the herring, was at one time supposed to be a native of foreign seas. 7. This fish is laden with spawn in May, and it has been known to deposit its eggs upon our shores in the following month. Such is a brief _resumé_ of Mr. Couch’s chapter on the mackerel. Now, we have no account here of how long it is ere the spawn of the mackerel quickens into life, or at what age that fish becomes reproductive, although in these two points is unquestionably obtained the key-note to the natural history of all fishes, whether they be salmon or sprats. In fact—and it is no particular demerit of Mr. Couch more than of every other naturalist—we have no precise information whatever on this point of growth power. We have at best only a few guesses and general deductions, and we would like to know as regards all fish—_1st_, When they spawn; _2d_, How long it is ere the spawn quickens into life; and _3d_, At what period the young fish will be able to repeat the story of their birth. These points once known—and they are most essential to the proper understanding of the economy of our fisheries—the chief remaining questions connected with fishing industry would be of comparatively easy solution, and admit of our regulating the power of capture to the natural conditions of supply. [Illustration: WHITEBAIT GROUND NEAR QUEENSFERRY.]