32 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



tion of this was afforded in an aquarium at Woods Hole iu the summer of 1892, when 

 a conch (Sycotypus canaliculattis) was placed in the same tank with a female lobster 

 which was nearly 10 inches long aud which had been in captivity about eight weeks. 

 The conch, which was of the average size, was not molested for several days, but at 

 last, when hard pressed by huuger, the lobster attacked it, broke off its shell, piece by 

 piece, and made quick work of the soft meat. 



On many parts of the coast the lobster does not find any lack of dead fish for 

 food. This is notoriously the case where seining is conducted on a large scale, as on 

 the coast of Maine. One of the great evils attending this method of taking fish is 

 the destruction wrought upon the young. In seining mackerel the catch is hoisted 

 upon deck, where the fish are sorted, the larger, which are marketable, being saved 

 while the smaller fry are thrown overboard. Owing to the rough treatment which 

 they receive, and especially the exposure to the suu, the smaller fish are thus said to 

 be destroyed by thousauds. The lobsters in the vicinity profit by this evil, playing 

 the part of scavengers. 



If a lobster which has fasted for a number of hours is fed with a little fresh meat, 

 such as a piece of clam or fish, the process of feeding will be found to be one of no 

 little interest. The lobster eagerly seizes a piece of food with the chela? of the third 

 and fourth pairs of walking legs, and passes it up to the third pair of maxillipeds, 

 which are held close together, each being bent at the fourth joint and folded on itself. 

 With the third maxillipeds thus pressing against the mouth, the food is kept in 

 contact with the other mouth parts, all of which are in motion, and their action is thus 

 brought to bear upon it. By means of the cutting spines of the appendages external 

 to the mandibles — maxilla; aud first and second pairs of maxillipeds — the meat is as 

 finely divided as in a sausage machine, and a stream of fine particles is passed con- 

 stantly into the mouth, being previously submitted to the action of the mandibles. 



If one wishes to watch the movements of the complicated mouth parts more 

 closely, he has only to take a lobster out of the water, place the animal upon its back, 

 aud when it has become sufficiently quiet stimulate the mandibles or the broad plate 

 of the large maxillipeds with the juice of a clam or the vapor of ammonia, which can 

 be squirted with a pipette. Masticatory movements are immediately set up in the 

 appendages, those belonging to the side stimulated usually working independently. 

 The two small chelate legs are also drawn up rapidly to the mouth, as if to hand 

 up pieces of food. 



When stimulated in this way the plates of the first pair of maxillpe come together 

 over the lower posterior half of the mandibles. The movements of the masticatory 

 parts of the second maxilhe are synchronous with the beating of the scaphognathite. 

 These project somewhat obliquely over the convex surfaces of the appendages in front, 

 inward, and slightly upward. The large plates of the first maxillipeds work up and 

 down, and at the same time inward toward the middle line, describing an ellipse. The 

 second pair of maxillipeds move alternately or together, inward and outward, with 

 slight up-and-down movement. The large maxillipeds move together, the toothed 

 margins meeting like the edges of a nutcracker (compare fig. 68, pi. 30), while the 

 three terminal joiuts are bent inward and somewhat downward, as in the case of the 

 second maxillipeds, so as to meet on the middle line below and hold the food up to 

 the mouth. 



