[19] OYSTER CULTURE. T71 
calcareous test or covering is sufficiently hard to completely protect them. 
The cray-fish change or shed their skin or test once a year, and this 
shedding takes place from May to September. During the shedding 
period the animal retires into some hole or sheltered place so as to protect 
itself from the thousand dangers to which its soft and defenseless body 
would subject it. It remains concealed for two or three days, in which 
time its new covering acquires nearly the solidity of the old envelope. 
Among the cray-fish and other crustaceans of the same family the feet 
and antenne possess the remarkable property of being renewed in case 
they are accidentally lost either in part or wholly. A few days after 
a leg is lost a reddish membrane forms over the place, covering and ob- 
literating the wound; soon a conical bunch appears, which elongates 
and finally bursts through the membrane and shows a small, soft foot, 
which increases in size, regains its calcareous test, and in a short time 
duplicates completely the lost member. The river cray-fish, which is 
also much sought after for food, is found in fresh-water streams through- 
out Europe, but it is quite particular in its choice of habitation. It 
loves clear, flowing water, where the bottom is composed of small stones 
and pebbles without mud, and where it can find protection and plenty 
of holes and crevices into which to retire, and which it leaves only to 
seek food, consisting of mollusks, little fish, and the larve of insects ; 
it also feeds upon, and even prefers a more wholesome diet, decaying 
animal substances, or dead bodies floating upon the water, and in de- 
fault of any of the above-mentioned articles it will make a bountiful meal 
of vegetables or young shoots. It lives for about twenty years, and as it 
increases in size at each moult, it may become relatively of considerable 
magnitude. It can be very easily acclimated in foreign waters, provid- 
ing the water is sufficiently pure and the surrounding conditions suita- 
ble to its existence; it also conforms readily to a state of confinement, 
and will readily develop and reproduce in small basins, analagous to 
those in general use for artificial fish culture. 
The lobster (Homarus vulgaris) may be known by its smooth carapace 
and greenish-brown, sometimes bluish, color, which, when cooked, changes 
to a pale red, thus diminishing a littie, when upon our tables, the repul- 
sive aspect characteristic of all crustaceans. The head of this animal 
is terminated anteriorly by a sort of three-pronged rostrum, and is armed 
with long reddish antenn# and two pedunculated eyes. The anterior 
pair of feet are armed with powerful pincers, which are often out of pro- 
portion to the size of the rest of the body.” The lobster is widely dis- 
tributed in the ocean, the British Channel, and the Mediterranean, and 
inhabits rocky bottoms, often at great depth. 
The rock-lobster (Palinurus vulgaris), which is nearly as much sought 
for as an article of food as the lobster, is distinguished by the large 
fan-shaped termination of its abdomen, by the five pairs of similar legs 
without pincers, by possessing long and strong antenne and a moder- 
ately long carapace covered, especially in front, with small points or pro- 
