500 PROF. J. E. DUERDEN ON CRABS [DeC. 12, 



grown Bunodeopsis fixed by its base. While walking about, the 

 crab accidentally came into contact witli the large Bunodeopsis 

 and stopped as if to examine it ; then by means of one of its first 

 ambulatoiy limbs it began woi-king around the base of the polyp, 

 and after a few minutes detached it. At the same time it moved 

 the claw holding the fragment of Bunodeopsis towards its mouth 

 as if to ingest the polyp, but the fragment was merely liberated 

 and left free in the dish, and the empty claw then seized upon the 

 larger Bunodeopsis which it had previously dislodged from its 

 substratum. The Melia had now a perfect bunodeopsid and a 

 sagartiid. At a later stage the large Bunodeopsis was removed 

 and the previously discai-ded fragment introduced into the dish, 

 when after a time the latter was appropriated. 



The fragment of Bunodeopsis and also a Sagartia wei'e again 

 placed in a dish containing a Melia with both its claws unoccupied. 

 These were taken up as soon as the crab came into contact with 

 them, and a second perfect sagartiid was then placed in the dish. 

 The crab with both its claws occupied came into contact with the 

 third actinian, remained near it for some time, and then pushed it 

 away. On returning fifteen minutes later, however, it was fovind 

 that the fragment of Bunodeopsis had disappeared, and its place was 

 occupied by the sagartiid ; the Melia had detached the bunodeopsid 

 fragment and had taken up the sagartiid in its place. There 

 appeai-ed to be evidence that the crab will tear a single actinian 

 in two in order to provide each claw with a polyp. 



Method of Holdixg and Seizing the Actinians. 



Usually the actinians Avere held so loosely within the chelijjeds 

 of the crab that the column was but slightly constricted. As men- 

 tioned by Mobius, the joints of the chelfe are provided with very 



Text-fiir. 75. 



Claw of Melia tessellata showing the two rows of spines. Much enlarged. 



minute spines, and these no doubt assist in maintaining the polyp 

 in position (text-fig. 75). Occasionally the body of the polyp was 

 held in such a manner that the column was not altogether within 

 the claws, and the wall would then be constricted and indented by 

 the tips of the claws. In preserved specimens the polypal tissues 



