220 
BULLETIN OP THE UNITED STATES FISH COMMISSION. 
(9) The adult lobster is essentially a nocturnal animal, being far more active by 
night than in the day. The reverse is true in the larval period, when the habits are 
entirely different. 
(10) Burrowing habits . — The lobster is a great borrower in the sea-bottom. This 
habit is developed to an extraordinary degree in pounds or inclosures, at all seasons, 
and is practiced, though less regularly, under other circumstances. (Compare para 
graph 8.) The holes, some of which are 2 to 3 feet long, are solely for protection and 
are never used while the animal is molting. In the construction of the holes the large 
claws are used, and possibly the tail-fan. The lobster almost always enters its burrow 
tail first. 
(11 ) Food . — The adult lobster feeds chiefly upon fish, dead or alive, and upon inver- 
tebrates. It also takes a small quantity of vegetable food, such as algae and eelgrass. 
Fragments of dead shells, coarse sand, and small gravelstones are also swallowed. 
The former yield lime, which is absorbed and finally laid down in the skeleton. Many 
small fish which inhabit the bottom fall a prey to the sharp cutting-claw of the lobster, 
which it uses with great skill and dispatch. The larger lobsters prey invariably upon 
the smaller or weaker ones when they can. 
(12) The food is seized, torn, and crushed by the large claws, and then taken up by 
the appendages about the mouth (maxillipeds, maxillae, and mandibles), by which it 
is successively torn and chopped fine, when this is possible. While the animal is 
eating, a stream of fine particles is passed into the mouth, thence to the gastric mill 
or masticatory stomach. Here the food is ground and the fluid or digestible parts 
are strained into the small delicate intestine from which they are absorbed. The 
indigestible refuse is regurgitated from the stomach-bag. 
(13) Impregnation . — In copulation the female receives the sperm from the male in 
packets or spermatophores, which are deposited in an external chamber, the seminal 
receptacle. This is a blue, heart-shaped structure, situated on the under side of the 
body, between the bases of the fourth pair of legs counting from the large claw-bearing 
appendages. It opens to the exterior by a median slit with elastic edges, which can 
be easily pressed apart. 
(11) The male does not discriminate the sexual condition of the female, which may 
be impregnated at any time. It is, however, probable that copulation takes place most 
commonly in spring. The sperm retains its vitality for a long time, in some cases 
for at least several months before it is used. 
(15) Egg laying . — Much confusion has existed concerning the time when the eggs 
are laid. This has resulted chiefly from the fact that the eggs are carried by the 
females for the space of from ten to eleven months before they are hatched. About 
80 per cent of the spawning females lay their eggs at a definite season in the summer 
months, chiefly July and August. The remainder, about 20 per cent of the whole 
number, extrude eggs at other seasons — in the fall and winter certainly, and possibly 
also in the spring. 
(16) In the western end of Vineyard Sound and the region about Woods Hole the 
greater number of eggs are extruded during the latter part of July and the first half 
of August. The summer spawning of each year lasts about six weeks, and fluctuates 
from year to year backward and forward through an interval of about a fortnight. 
(17) This variation in the time of the production of the eggs is due to the fact that 
the ovarian ova require at least two years of growth before they are ready for 
