ARPACTICUS. 
213 
The thorax consists of four, the abdomen of six seg- 
ments, the terminating one giving issue to two long, linear, 
finely-serrated setae, fully the length of the body. The 
upper or cephalo- thoracic segment, comprising the head, 
consolidated with it, is beaked, having a short conical 
elongation in the centre. 
The antennae (f. 3 a) are short, of about ten articula- 
tions in the female, and at the junction of the fourth with 
the fifth there is a small lateral joint in both sexes. At 
the fifth ring, in the male, is situated the swelling and 
hinge-joint. The antennules (f. 3 b) consist of two arti- 
culations, the first having a shoot sent off from about its 
centre, divided into two joints, which are furnished with 
several hairs ; the second being terminated by five setae, 
the three internal of which are the longest, and have a 
joint near the middle of their length. 
The mandibles (f. 3 c) resemble very much these organs 
in the Canthocamptus minutus , the teeth, however, being 
more distinctly seen. The posterior foot -jaws (f. 3 e) are 
composed of three articulations, the first being long, the 
second short and curved, and the third forming a strong 
curved hook, the two terminal combined having the ap- 
pearance of a strong claw. 
The first pair of feet (f. 3 /) consists of two unequal 
stalks, arising from a common base of considerable length. 
The superior is the longer of the two, and is composed of 
two nearly equal stalks, serrated on their upper edge, the 
second terminating in three short hooks. The inferior 
stalk is also formed of two articulations, the first of which 
is much the longer of the two, and is serrated, the second 
being very short, and terminating in two curved hooks. 
The three other pairs of feet (f. 3 g ) consist, each stalk, of 
three articulations, furnished with long hairs, one or two 
of the long terminating ones being finely serrated. The 
external stalk is larger and longer than the internal. All 
three pairs of feet resemble each other. 
The supports or fulcra (f. 3 d) are composed each of a 
