STUDY ON THE HABITS OF THE CRAB. 



I6 7 



TABLE I. 



The letters refer to the four modes of cutting. The Roman numbers designate 

 individuals, the Arabic ones the number of times for every crab and every category. 



Never did the maximum number belong to the category D, 

 which means that in 180 cases out of 200 Dromia started the 

 work at the middle of one side of the rectangle, or at the corner. 

 Some individuals, as IV., VI., VIII. and X. showed a very 

 striking predominance of one definite mode of cutting and to a 

 certain extent it may be concluded that a definite fashion of 

 working is connected with definite individuals. 



Similar modifications of the mode of working were observed 

 when Dromia had to cut its case out of a sponge instead of the 

 paper. The sponge was taken from a larger individual and given 

 to a smaller one. The crab always cuts the sponge round and 

 adjusts it to its own size and shape. The sponge is much thicker 

 and less compact, as compared with the paper and therefore the 

 crab was obliged to tear off small pieces of it instead of tearing 

 it as a whole. The pieces, detached from the sponge were then 

 directed towards the mouth where the maxillipedes held them 

 for a while and then let them drop; the current which brings 

 the water to the gill-chamber carried them away. As in the 

 case of paper, Dromia may perform its work while lying on its 

 back or in the normal position of the body. The sponge is held 

 tightly by means of 4th~5th pairs of legs. Sometimes the crab 

 will carry on its back a sponge which is much larger than the 

 normal case and will start the work only after a considerable 

 time. But sooner or later the sponge always becomes adjusted 

 to the size of the animal. 



A very interesting reaction occurs when we put into the 

 aquarium a large stone covered with a sponge. The animal very 

 soon climbs upon it, grasps the sponge at two points, and tries 

 to tear it off from the ston-e. After some unsuccessful attempts 



