FREE MESSMATES. 15 



same habits, can sometimes only be distinguished from 

 each other when we have made our observations on 

 them in their first swaddUng clothes. The child has 

 given a clue to the history of the old man. 



We will not examine these animals in all the details 

 of their private hfe, and yet we are strongly tempted to 

 confess to our readers some of the indiscreet acts of which 

 we have been guilty, in watching them while changing 

 their dress. Notwithstanding their shyness and their 

 desire to escape observation during the moulting period, 

 we have more than once made observations on them 

 while quittmg their garment which has become too small. 

 The old tunic generally splits down the back, and falls 

 off all in one piece as it gives the animal egress. The 

 crustacean is extended quite soft and supple by the side 

 ' of its rigid carapace. 



Of all the free crustacean messmates, one of the 

 most interesting, though among the smallest of them, is 

 a tiny crab, about as large as a young spider, which 

 lives in mussels, and which has been often accused, 

 though evidently wrongfully, as the cause of the indis- 

 position so well known by those who are fond of this 

 mollusc. Very many of them have been seen within the 

 last few years, and yet accidents have been very few. 

 The mussels themselves are guilty; they produce on 

 some persons an injurious effect, through idiosyncracy . 

 We have at least a word to serve as an explanation, and 

 at present we must content om-selves with it. 



Under what conditions do those crabs, called by 

 naturalists Pinnotheres, and which we do not find else- 

 where, inhabit mussels? Are they parasites, pseudo- 

 parasites, or messmates ? It is not a taste for voyaging 



