30 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



frequently met with, and in lobsters from 3 to 4 inches long-, under very peculiar cir- 

 cumstances. (See pp. 89 and 90.) Coarse sand and gravel-stones, occasionally as large 

 as duck shot, may also be found in tlie stomach, but with no marked regularity. 

 These are not necessary for grinding the food, as in the gizzards of fowls, since the 

 walls of the lobster's stomach are furnished with an admirable masticatory apparatus; 

 still, whether of accidental occurrence or not, they can hardly fail to serve a useful 

 purpose. 



In the course of this investigation of the habits of the lobster, the stomachs of 

 large numbers of these animals were carefully preserved during a period of seven 

 months (December to June). They were all captured in the harbor of Woods Hole, 

 Massachusetts, under the conditions described on p. 25. A considerable number 

 of these stomachs were empty; more than half contained remnants of recently devoured 

 fish, a mass of scales and bones, mixed with fragments of the indigestible parts of 

 other organisms. In many cases it was quite evident that the bait of the traps 

 formed the only food found in their stomachs. 



The lobster undoubtedly regurgitates the insoluble and indigestible parts of 

 its food. That the crayfish possesses this power was shown by the experiments of 

 Lemoine (118). When the buccal cavity was stimulated by electricity, antiperistaltic 

 movements were set up in the remaining parts, until the contents of the stomach 

 escaped by the mouth. It was thus proved that the oesophagus was capable of two 

 kinds of movements — peristaltic and antiperistaltic. Some such outlet for waste 

 matter is absolutely necessary in an animal where the fluid or finely divided and 

 digestible parts of the food only can pass into the delicate intestine. The hard parts 

 of fish, mollusks, and Crustacea appear to be retained until they have given up a good 

 deal of their lime, thus contributing to the calcareous supply of the exoskeleton. 



The stomachs examined contained remnants of the following organisms placed in 

 the order of their relative abundance: fish (procured independently of the traps); 

 crustacea, embracing chiefly isopods and decapods; inollusca, consisting largely of 

 small univalves; alga?; echinoderms and hydroids. The bones of fish showed them 

 to belong, as a rule, to small individuals or species. Among the crustacean remains 

 parts of the small mud-crab, Panopajus (P. sayi and P. depressus, the common species 

 in Vineyard Sound) were almost invariably recognized, and it was not unusual to find 

 parts of the skeletons of small lobsters. The isopod, Civolana concharum, is frequently 

 eaten by the lobster, often in large numbers. This species is a scavenger, and 

 devours the bait used in the traps, which explains its common occurrence in the 

 stomachs of lobsters recently caught. In one case, that of a female captured in January, 

 the stomach was filled with fresh lobster eggs in an advanced stage of development. 

 These were not taken from any lobsters in the trap, but under what circumstances 

 they were obtained one can easily conjecture. The egg-lobster is undoubtedly a shining 

 mark, not only for outside enemies, but even for members of its own species. The 

 larger mollusks are eaten by crushing the shells and picking out the soft parts, while 

 many of the smaller species are swallowed entire, and afterwards pulverized in the 

 gastric mill. Echinoderms probably enter largely into the diet of the lobster, wher- 

 ever they abound. Parts of the common starfish (Asterias forbesii) and rarely a few 

 spines of the sea-urchin (Arbacia punctulata) were detected, but it might be that the 

 latter were swallowed together with other calcareous fragments. Very little change 



