EMRRYOLOGY AND I\ IETAMORPIIOSIS. The lob ster has a much shorter larval life than most deeapod crustacea, and its development is in fact direct, its metamorphosis being incomplete. The period of incubation at Woods is about ten months, front the middle of July or August to the middle of the following _Alay or June. In one ease the eggs were carried 335 days, front July 1, 1890, to June 1891. The yolk segments in about twenty-four hours after o•iposition, and the embryo passes through the nauplius condition in ten days, and when from 26 to 28 days old the eye-pigment can be seen at the surface. The process of hatching for all the eggs borne by one female requires about a week.
The young on hatching are driven away by the fanning motion of the parent, and in :May, .June, and July they abound at the surface. During this time and until the fourth stage is reached im mense numbers are devoured by surface-swim ming fish and other animals. Herrick states that a survival of two in every 10,000 larvae hatched would maintain the species at an equilibrium, and the destruction of the young under the pres ent conditions of the fishery is probably even greater than this implies. After hatching, the young lobster passes through three stages before assuming the adult shape. In the first stage (Fig. 1), which lasts from one to four or five days, the length of the body being a little over a of an inch (7.84 min.), there are no abdominal appendages, and the two pairs of antennae are short and thick. It now (lifters, however, from the larva (zoga) of most shrimps and crabs, in having the full of thoraeie legs. In the second stage. which lasts from two to five clays, the length being 9.2 mm., four pairs of swimmerets have appeared, and in the third stage the last pair of abdominal legs (uropods) arise. This stage lasts from two to eight days, its body being 11.1 ann. in length.
in Narragansett Bay (Wickford ) the average period fur hatching and teaching the fourth stage was a little over twelve days. The length of the fourth stage varies front 10 to 19 days; and during this period the larva is about half an inch (12.5 mm.) in length.
After the third molt. the young lobster or lobsterling rig. 4) assumes the shape and habits of the adult. Its hotly beeon.es heavier, the ehehe or hands of the first pair of feet are held straight out, and aftt r living at the surface front six to eight weeks it sinks to the button), over which it crawls. and now the habits change. The young lob.-ter. pre
viously without fear and moving aimlessly about at the surface. now appears and retreats from danger. as does the adult : after reaching the bottom it travels toward the shore, and borrows in the sand at the bottom under stones, and takes every precaution to avoid its 'enemies.' Its nat ural food consists of minute crustaceans (cope pods), and when food is scarce its own breth ren, as it is atrociously cannibalistic.
Mot:risn. The periodical shedding of the skin begins when the lobste•lings are two or three days old. and continues throughout life. the intervals between the successive castings of the shell growing. longer with age. It molts from 14 to 17 times the first year of its life. After sexual maturity eedysis may not occur more than once a year; a lobster has molted front 25 to 26 times.
In the first molts, as in those succeeding. the process is the same, the old skin being split across the hack, between the hinder of the shield or carapace and the abdomen: the carapace is raised up behind. the body being gradually drawn out through the gaping opening. In adult lob sters the withdrawal of the contents of the big claws is facilitated by the partial absorption of the lime in the shell of the narrow part of the base of the leg, so that the integument can be distended. The muscles at this time are greatly stretched, while their :teflon is probably aided by the removal of water from the blood During the process the stomach with the solid teeth, as well as the ehitinous lining of the (esophagus and intestine. are east off with the entire integument. including the finest hairs fringing the appendages. 'Shedders' are those with shells 'hard and dull.' previous to shedding or casting their shell, while soft-shelled lobsters are those which have recently &mil:kited. The process occupies but a few unless through weakness it is delayed. The period of shedding, is. as in insects and other animals. a preea•1011: one, and sometimes the animal dies during the process; both in the larval and adult stages growth or increase in size takes place while the new shell is being formed, and not immediately after eedysis. (Herrick.) The in crease in length of a lobster five and one-half inches long is one inch; in one 11 inches long one and one-fourth inches. The appearance of sudden growth is due to the absorption of water, not cellular growth. After molting it is several weeks before the new shell is as hard as the old one.