1. It has been previously stated that some of the mussels are spawning, or with spawn, during any period of the year. Many of the most important species are spawning during the late spring, early and mid summer; other equally important species form their eggs in the late summer, when they become fertilized and develop into the glochidium stage, but the mother clam retains them in marsupial pouches within her shell during the entire winter and even into the summer. All species of mussels carry the eggs in the marsupial pouches during the process of development to the glochidium stage or longer, whether the period be for a few weeks or for a few months. In this condition the mussels are said to be gravid. It is readily observed that when gravid mussels are disturbed they frequently discharge the young, regardless of whether these are mature enough to be liberated from the parent or not; certain species, such as the niggerhead, are particularly likely to do this. In the commercial fishery, therefore, not only is much spawn destroyed when large gravid mussels are captured, but it is quite probable that other mussels, disturbed on the bottom, though not captured, are caused to abort the young in an immature stage when they are entirely unable to complete the development without the parent. 2. In the stage of existence immediately after liberation from the parent, the young mussels are parasitic upon fish. We are not here concerned with them during this period of the life history. When they are dropped from the fish many of the young mussels do not at once take up life in the sand or mud of the bottom, but we find them forming delicate threads by which they hang from plants or sticks or stones or from clam shells, and thus are kept from being washed away or smothered in the mud of the bottom. We may imagine the harm to these little mussels that is unavoidably wrought when the beds are continually dragged over. In like manner, the little shells that are just beginning to take hold in the bottom may be torn out by the rake or hooks, to be smothered or washed away to less favorable bottoms. It will be remembered that when mussels first begin life in the thread stage or in the bottom if the thread stage is omitted, they are too small to be found without a microscope. 3. One of the principal methods of capturing mussels is with the bar and hooks dragged over a large area of mussel bed in taking a relatively small number of shells. There is chance for these hooks to injure many little shells when each drag, requiring a period of only a few minutes, covers a space of bottom 16 feet wide and several hundred feet long. Nevertheless, it is not certain that there is any method to take its place, and any implement used will accomplish some injury to the very youngest mussels. CONSIDERATIONS DETERMINING SIZE OF CLOSED REGIONS.