Miscellaneous. 211 



this feeding lasts the annelid gives no external sign of life : it 

 awaits the favourable moment. 



But the procedure is different when we give the crab a morsel of 

 large size, as, for instance, a half or a quarter of a cockle {Cardium). 

 Well pleased with this prize, the crab is seen to masticate it 

 forthwith with animation ; it even protrudes a portion of its body, 

 and feeds, if I may be permitted to use the expression, like a glutton. 

 But almost immediately, between the cephalothoras and the bases 

 of the limbs on the right side, the anterior portion of the worm is 

 seen to make a slow forward movement. The creature, without 

 hesitation, proceeds to explore its comrade's mouth ; on encounter- 

 ing the morsel of cockle there, it nips it forcibly with its powerful 

 mandibles and thenceforth does not relax its hold. Retracting its 

 body, it draws the booty to itself. Then one of two things 

 happens : either the hermit-crab also clings to the prey, without 

 noticing, moreover, the cause of its impending loss, and the annelid 

 redoubles its efforts so effectually that the fragment is finally torn in 

 two; whereupon the worm drags its portion into the interior of the 

 shell, to devour it unmolested. Or else the crab lets go its prey, 

 and the annelid carries it off bodily ; in this manner I have seen 

 the worm take away a Cardium almost whole, so that it could 

 not even make it pass through the narrow orifice left between the 

 crustacean and the shell. By dragging very hard, however, the 

 annelid almost always succeeded in accomplishing its purpose. 



There is no need to believe that the worm perceives the near 

 presence of prey by smell, for, as I have been able to determine by 

 withdrawing it from the shell, its organs of sense are greatly dulled. 

 It is curious to find that it is the hermit-crab itself that, uncon- 

 sciously of course, informs its corai-adc of the presence of prey of 

 considerable size ; the irregular movements in which the crusta- 

 cean indulges indicate to the annelid that it is time to show itself: 

 the worm is never seen to emerge at any other time. Another fact 

 of interest to be noted is the indifference of the crustacean with 

 regard to the robber with which it lives and which, to use a popular 

 expression, comes to " snatch tlie morsel out of its mouth." I have 

 often seen the annelid, after the hermit-crab had inadvertently let 

 its prey fall, introduce its head and the foremost annuli of its body 

 between the maxillipeds and right into the mouth of the crustacean. 

 Apparently nothing would have been easier for the latter than to 

 ingest the worm and to rid itself of it once for all ; but it left it 

 absolutely alone. The NereUepas profits by the opportunity to 

 devour the fragments of food that still remain in the mouth of the 

 crab, and to carry them off into its retreat. 



The above observations were made in aquaria. There is no 

 doubt, considering their frequency, that the phenomena take place 

 in the same way in a state of nature at the bottom of the sea. The 

 annelid feeds upon the large substances that the hermit-crab intends 

 to devour. But perhaps it will be asked whether, in addition, the 

 worm does not eat, if not the whole, at least a portion of the faeces 



