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Show 500 PROF. J, E. DUERDEN ON CRABS [Dec. 12, grown Bunodeopsis fixed by its base. While walking about, the crab accidentally came into contact with the large Bunodeopsis and stopped as if to examine i t ; then by means of one of its first ambulatory limbs it began working 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 pi'eviously discarded fragment introduced into the dish, when after a time the latter was appropriated. The fragment of Bunodeopsis and also a Sagartia were 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 found 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 appeared to be evidence that the crab will tear a single actinian in two in order to provide each claw with a polyp. M e thod of H o ld ing an d S e iz in g th e A c t in ia n s . Usually the actinians were held so loosely within the chelipeds of the crab that the column was but slightly constricted. As mentioned by Mobius, the joints of the chela? are provided with very Text-fig. 75. Claw of Melia tessellata showing the two rows of spine6. 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 |