BRACHYURI. 169 



whence, the vessel containing specimens designed for permanent obser- 

 vation, must be carefully emptied and replenished within a few hours 

 after feeding ; or the specimens should be transferred to different vessels, 

 which is safer^ — repeating replenishment next morning, or sooner. Fre- 

 quent inspection of aU such captives is indispensable. 



Individuals of the Common Crab, when alone, become very tame 

 and tranquil ; indeed, they seem to be among the tamest and most tran- 

 quil of the tribe ; — whence, for a long time, I was induced to think 

 them of very pacific nature. But four small ones having been com- 

 mitted to the same vessel, I was then undeceived by discovering that 

 one of them had been devoured by a companion, two of the four being 

 larger than itself. On the same day, I found the smallest of the three 

 survivoi's in the fangs of the largest, which was more powerful, nor 

 could I rescue it without the loss of several of its hmbs. 



This mutilated subject l:)eiug shifted to another vessel, it was with 

 some surprise that I saw it immediately begin to feed on portions of 

 mussel which I supplied. 



Now, it proved to have undergone an extraordinary mutilation. 

 Seven of its ten external organs were actually gone ; for only the two 

 claws and the posterior right limb remained. Nevertheless, these were 

 entire, and next day the animal seemed quite well, — consuming the re- 

 mainder of the mussel beside it. The mutilation occurred on October 

 20th, and delineation followed on the 3d of November. — Plate XLI. 

 fig. 1, back ; 2, breast. 



This incident afforded ample evidence, that notwithstanding the 

 pacific disposition of the species, presumed from apparent tranquillity, 

 the weak were not to be trusted in the society of the stronger. 



Ninety-four days after mutilation, the victim cast its shell. The 

 new animal came in very pale, almost white, and what was more re- 

 markable, with the whole complement of ten limbs entire. Those cor- 

 responding to the seven which had been deficient, seemed to me some- 

 what under the natural size. The posterior limb on the left side, corres- 

 ponding to that mutilated, was smaller than its fellow on the right, 



T 



