attachment 5, which is slender) have a thick 

 base, whence they taper to a point, and a very 

 few bristles appear upon the surface. They 

 are almost invariably curved downwards, and 

 appear to be used to draw the surface of the 

 mullusc to the mouth c, and retain it there. 

 This action of the palpi would draw the body 

 forwards, but the claws of the posterior pair of 

 legs (which are seldom used in locomotion) act 

 in a contrary direction. The 'eyes' are black 

 points situated beneath the integuments, and 

 they are probably insensible to light. They 

 are frequently drawn forward to a distance 

 rather less than their diameter, when they 

 return to their usual position. 



They are very hardy, and will live two 

 weeks in vessels without food. They do not 

 appear to suffer from cold, as they are pretty 

 active in water a few degrees above the freezing 

 point; and I have found them moving about in 

 a Unio, the outside layer of which was frozen. 

 Nevertheless, they become torpid instantly, if 

 placed in freezing water, and the torpidity re- 

 mains but a short time, if the temperature be 

 gradually raised. 



