ARPACTICUS. 215 



distinct from each other. The thorax is composed of four 

 segments, and is large and rounded. The abdomen con- 

 sists of six slender segments, the last being bilobed, and 

 giving off two long setae and two short ones. The whole 

 animal is beautifully coloured with green, red, and purple. 

 The eye is large, of a ruby colour. 



The antennae (t. XXVIII, f. 2 a) are short, divided into 

 seven articulations, all of which are setiferous. The first two 

 are short and stout ; the third is much longer, toothed on 

 its upper edge, and giving off at its extremity several long 

 setae. The last four are small and short. 



The antennules (f. 2 b) are composed of two seg- 

 ments, the first giving off a shoot from about the middle 

 of its length, and the second terminating in several stout 

 setae. 



The mandibles and anterior or first pair of foot-jaws 

 are strong, and resemble the same organs in Cyclops 

 quadricornis. The posterior foot-jaws (f. 2 d] are shorter, 

 but much stouter than those of the preceding species, 

 and consist, as in them, of the two joints and strong 

 terminal hooked claw. The thoracic pair of feet (f. 2 e) 

 differs in structure from the others. It consists of two 

 stalks, rising from a common base ; the anterior or upper 

 stalk composed of one long joint and a very short one, 

 which terminates in a strong claw, the posterior or in- 

 ferior stalk being very short, toothed on its edge, and 

 giving off several stout setae. The abdominal feet re- 

 semble those of preceding species, the setse with which 

 they and the fulcra are provided being ah 1 plumose. The 

 fulcra (f. 2 c] resemble those of chelifer. The setae of the 

 caudal segment, however, are not plumose. 



This species is at least three times larger than the pre- 

 ceding, and the body is stouter and more rounded. 



Hob. Along with preceding in Berwick Bay, 1835. 

 Dover, North Foreland, September 1849. 



