STUDY ON THE HABITS OF THE CRAB. 



animal stands on its head (Fig. 2D). At the same time the 

 position of the sponge is gradually altered : its fore edge becomes 

 inclined towards the abdomen and the sponge becomes almost 

 vertical in position touching the ground with the fore edge 

 (Fig. 2.D). As a consequence the abdominal end of the body 

 moves along the concavity of the sponge upwardly and, as the 

 back of the animal remains pressed tightly to the sponge, Dromia 

 while standing on its head assumes its normal position towards 

 the sponge. This means that the fore edge of the sponge touches 

 the head. The vertical position of both crab and sponge is of 

 course, a position of an unstable equilibrium, and therefore either 

 the animal falls forward, assuming the normal position, or it 

 falls on its back. In the latter case it can turn in different ways, 

 as described in the paper of Dembowski. 



The grade of lifting of the abdomen above the ground may be 

 very different and sometimes the position of the longitudinal axis 

 of the body may be only slightly oblique towards the bottom of 

 the aquarium. 



2. In other cases, Dromia approaches the sponge, turning its 

 abdominal end to it. The sponge still lies with its cavity directed 

 upwardly. When the abdomen touches the edge the hooks of the 

 4th and 5th pairs of legs grasp the inner surface of the sponge 

 near its edge (Fig. 2(7) and then suddenly contracting these legs, 

 the crab simply flings the sponge on the back. In the majority 

 of cases the animal approaches the sponge at the right spot, in 

 others it turns the case correspondingly, either before putting 

 it on the back, or later, in its definite position. 



3. There occurs sometimes a modification of case 2. The crab 

 approaches the sponge directing its head towards it, climbs over 

 the sponge and goes farther still in the same direction until 

 the fore end of the body touches the ground on the opposite side 

 of the meeting point (Fig. 2G). When only the abdominal end 

 remains in the concavity of the sponge the legs of 4th~5th pairs 

 grasp its inner surface near the edge and fling the sponge on 

 the back. 



4. In still other cases Dromia enters the sponge (always lying 

 with its concavity directed upwardly) and turns on the back, as 

 shown in Fig. 2.E. The animal changes its position towards the 



