158 HISTORY OF BRITISH CRUSTACEA. 



Division EDRIOPHTHALMA, Leach 



In the Crustacea of this division the eyes are sessile, that 

 is, are not elevated on foot-stalks, while the body is more 

 or less 'distinctly divided into three parts; the different 

 parts of which the thorax and abdomen consist are almost 

 always very distinct from each other, and movable. There 

 is no great dorsal shield corresponding to the carapace of 

 the PodophtJialma, neither do they breathe, like the latter, 

 by means of gills, but by the aid of a portion of their limbs, 

 the structure of which is wholly or partially modified for 

 this special purpose. 



The animals of this division are small in size and mostly 

 found in the sea or on its shores, where they abound ; and 

 by the removal of decaying animal and vegetable matter, 

 they effect great good, while they afford ample stores of 

 food to many fishes and sea-birds. 



Order AMPHIPODA. 



The abdomen, in the species of this order, is always well 

 developed, and furnished with five to six pairs of limbs. 

 The head is formed of a single segment, and has generally 

 only two sessile eyes and two pairs of antennae, though in a 



