GENERA CUM A, ALAUNA, AND BODOTRIA. 



333 



" In their habits all these animals seem to agree. I have not 

 been able to observe anything peculiar in them. They swim with 

 very great rapidity, and on stopping they fall to the bottom on the 

 sand or gravel, without attempting to lay hold of anything, as I 

 have already remarked, seldom using their feet as a means of pre- 

 hension. They free themselves with great dexterity from any 

 weight which may happen to fall on them. I have often placed 

 the point of a needle on their thorax and pressed them down into 

 the sand ; the animal immediately frees itself with very little ap- 

 parent trouble, by means of its tail. The extremity of the tail is 

 placed against the needle with one of the styles on either side of 

 it, and by pressing upwards in this way, it soon regains its 

 liberty. 



" They frequent sandy banks, and chiefly those where there is a 

 little sea-weed." 



