THE CRUSTACEA OF NEW JERSEY. 337 



water during the fall and spring, these movements varying with 

 the coast and nature of the bottom and influenced by oceanic 

 temperatures, abundance of food, and to some extent by moult- 

 ing and breeding habits. Lobsters often stay in relatively 

 shallow and cold waters of harbors through the winter, but 

 then they are only found on rocky bottoms, where food is most 

 abundant. They seem to prefer a temperature of about 50°. 

 In severe winters they are either driven into deep water, or if 

 living in harbors seek protection by burrowing in the mud. In 

 such cases a prolonged cold spell may prove fatal. 



When adult the lobster is essentially nocturnal, though in the 

 larval state the reverse is true. The lobster is a great burrower, 

 making holes with the larg"e claws and tail-fan, sometimes two or 

 three feet in length. These burrows are never used when moult- 

 ing, and are solely for protection. The burrows are almost 

 always entered by the lobster tail first. The adult lobster feeds 

 chiefly on fish, dead or alive, and also invertebrates. It also takes 

 a small quantity of vegetable food, such as algje and eel-grass. 

 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 living on the 

 bottom' fall a pray to the sharp cutting claw of the lobster, which it 

 uses with great skill and dispatch. The larger lobsters prey in- 

 variably upon the smaller and weaker ones they may find. The 

 food is seized, torn and crushed by the large claws, and is then 

 taken up by the appendages about the mouth (maxillipeds, maxillse 

 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 re- 

 gurgitated from the stomach bag. 



In copulation the female receives the sperm of the male in 

 packets or spermatophores, which are deposited in an external 

 chamber (the seminal receptacle). This is a blue heart-shaped 

 structure, placed on the lower side of body between bases of 



22 MU 



