(3) The female may be impregnated or provided with a supply of sperm for future use by the male at any time, and the sperm, which is deposited in an external pouch or sperm receptacle, has remarkable vitality. Copulation occurs commonly in spring, and the eggs are fertilized outside the body. (4) Female lobsters become sexually mature when from 8 to 12 inches long. The majority of all lobsters 10-1/2 inches long are mature. It is rare to find a female less than 8 inches long which has spawned or one over 12 inches in length which has never borne eggs. (5) The spawning interval is a biennial one, two years elapsing between each period of egg-laying. (6) The spawning period for the majority of lobsters is July and August. A few lay eggs at other seasons of the year--in the fall, winter, and probably in the spring. (7) The period of spawning lasts about six weeks, and fluctuates slightly from year to year. The individual variation in the time of extrusion of ova is explained by the long period during which the eggs attain the limits of growth. Anything which affects the vital condition of the female during this period of two years may affect the time of spawning. (8) The spawning period in the middle and eastern districts of Maine is two weeks later than in Vineyard Sound, Massachusetts. In 1893 71 per cent of eggs examined from the coast of Maine were extruded in the first half of August. (9) The number of eggs laid varies with the size of the animal. The law of production may be arithmetically expressed as follows: _The number of eggs produced at each reproductive period varies in a geometrical series, while the length of lobsters producing these eggs varies in an arithmetical series._ According to this law an 8-inch lobster produces 5,000 eggs, a lobster 10 inches long 10,000, a 12-inch lobster 20,000. This high rate of production is not maintained beyond the length of 14 to 16 inches. The largest number of eggs recorded for a female is 97,440. A lobster 10-1/2 inches long produces, on the average, nearly 13,000 eggs. (10) The period of incubation of summer eggs at Woods Hole is about ten months, July 15-August 15 to May 15-June 15. The hatching of a single brood lasts about a week, owing to the slightly unequal rate of development of individual eggs. (11) The hatching period varies also with the time of egg-laying, lobsters having rarely been known to hatch in November and February. (12) Taking all things into consideration, the sexes appear about equally divided, though the relative numbers caught in certain places at certain times of the year may be remarkably variable. (13) Molting commonly occurs from June to September, but there is no month of the year in which soft lobsters may not be caught. (14) The male probably molts oftener than the female.