SECT. vii. CRUSTACEA. 201 



five plates spreading like a fan. All the bristly feet, 

 which seem to hang loosely down from the animal, are 

 fitted for swimming ; those of the tail have long ciliated 

 plates in their basal joints. These creatures are small, 

 and inhabitants of warm seas. 



Ampliipoda. 



The Amphipods are very numerous, and abound in the 

 British seas. They have long, slender, and many-jointed 

 bodies which have no carapace : the tail in some genera 

 is more fitted for swimming, in others for leaping. The 

 Talitrus, or Sandhopper, common on every sandy shore 

 in Europe, is a well-known example of the leaping genus. 

 It is very small and exceedingly active. The upper an- 

 tennse are very short, the inferior pair are large, and 

 longer than the whole body. The anterior feet are thin 

 and not prehensile. The first pair end in an immov- 

 able claw ; the second pair have a kind of hand, and 

 are folded beneath the body; the following feet end in 

 a crooked nail. The appendages of the last three rings 

 of the tail are thick and spiny, and the tail serves as a 

 leaping organ. 



The sandhoppers hide themselves between tidemarks 

 in large communities under masses of wet sea- weeds, on 

 which they feed. When disturbed they leap away with 

 great agility, and bury themselves in the sand by dig- 

 ging with their fore-feet, and kicking the sand away 

 with their tail-feet. They have a strong sense of smell, 

 for if a dead fish be buried in the sand, it is devoured 

 by these little voracious animals in a few days. 



In the fin-tailed genera the gills are suspended be- 

 tween the bases of the thoracic legs : they swim lying on 

 their side, and their feet are very varied in form, but 

 always more or less furnished with spines and hairs. 



There are several genera of Amphipods that are nest- 

 building animals; all have hooks at the end of their tails, 



