The marine genus Bryopsis grows in New Zealand, the Falkland Islands, and the seas about Cape Horn. The species are mostly parasites on other Algæ, and produce innumerable zoospores. The genus Codium is found in high latitudes, and appears under four different forms on the British coasts; one of these inhabits turfy banks exposed to the spray of the sea, the others grow in deep water, or on rocks never uncovered but at spring tides. Species of this genus are found as far south as Kerguelen’s Land, and in most of the intervening latitudes. The Caulerpas inhabit the warmer districts in the northern hemisphere, and furnish five species in New Zealand. The numerous species afford almost the whole food of turtles on many coasts, and other genera furnish nutriment to a host of smaller animals.[39] The Achlya prolifera is also a unicellular plant, much smaller than the Vaucheria, but whether an Alga or a Fungus is not very clearly settled. To the naked eye it appears as a cluster of colourless threads on dead flies floating in water, on the gills of fishes, and sometimes on frogs. With a microscope the tufts are seen to consist of tubes extending in all directions, filled with a nearly colourless granular matter, the particles of which are seen to move slowly in streams along the walls of the tubes, the currents sometimes anastomosing with each other. When the plant is about thirty-six hours old, the endochrome begins to accumulate in the dilated ends of the tubes, and is cut off from the remainder by a transverse division, the motion of the particles being still visible in the part cut off. The endochrome breaks up into a number of long masses, each of which acquires a cell wall and two cilia, and begins to move about within the parent cell; when mature they are set free by the rupture in its wall, and germinate, and produce a facsimile of the parent. It appears that, in some species, the transverse dividing film becomes convex as soon as the motile bodies are discharged, a new fertile articulation is formed and new motile spores are set free, and this process is continued till the vital powers of the plant are exhausted. The Achlya has resting spores, which may remain long in the water without change, but if a dead insect be put into it, they fix on it and germinate immediately. It is supposed that these resting spores are fertilized by filamental bodies. The Achlya prolifera goes through all its changes in an hour and a half or two hours. It is found in the thermal springs at Vichy, Nevis, and Vaux, where it contains an alkaline iodide.