32 
BULLETIN OE THE UNITED STATES FISH COMMISSION. 
tion of this was afforded in an aquarium at Woods Hole in the summer of 1892, when 
a conch ( Sycotypus canaliculatus) was placed in the same tank with a female lobster 
which was nearly 10 inches long and 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 hunger, 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 sun, the smaller fish are thus said to 
be destroyed by thousands. 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 chelae 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 — maxillae and 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, 
and 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 maxilla; come together 
over the lower posterior half of the mandibles. The movements of the masticatory 
parts of the second maxillae are synchronous with the beating of the scapliognathite. 
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 joints 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. 
