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



carefully separate an acfcinian from its attachment (text-fig. 76). 

 The crab moved round the actinian, inserting the tip of its limb 

 at intervals, until in the end the polyp was dislodged, when it was 

 seized and borne away. 



Text-fig. 76. 



3Ielia feftseJJaia dislodging a fixed actinian by means of its first 

 ambulatory limb. 



The crab Melia has thus the remarkable power of being able to 

 detach a sea-anemone fixed to a substratum, proceeding in abso- 

 lutely the same way as would a collector in endeavouring to secure 

 the same kind of animal. Manifestly it is only by some such 

 method that the actinian can be freed without injury, as the 

 chelae, along with the other appendages, are almost useless as 

 grasping-organs. In other instances where crabs mask themselves 

 by hydi'oid, sponge, or algal growths the fragments are simply 

 torn away by the chelipeds, but the dislodgment of an entire 

 actinian without injury and without the use of the claws is an 

 operation much more complex in character, whether we regard it 

 as an instinctive or an intelligent act. 



When first grasped by the ciabs the sea-anemones were not 

 necessarily held in the most favourable position, that is, across 

 the middle of the column with the disc directed upwards ; at the 

 beginning the chelae seized them in almost any fashion, so that 

 the disc and tentacles were directed at an angle. In one instance, 

 an actinian which had been thus grasped in an ii'regular manner 

 was turned towards the maxillipeds and there held in position 

 by the first ambulatory limbs ; the chela was then freed from 

 the actinian, cleansed thoroughly, and finally seized the actinian so 

 that it was held across the middle with the disc directed ujjwards. 

 There seems some evidence also that the actinians themselves 

 institute righting reactions, such as they carry out under more 

 natural conditions ; so that, although at first grasped in any 

 position, they are ultimately held across- the middle with the 



