1380 



CRUSTACEA. 



The general form in figures 9 and 10 is the same, the carapax being 

 triangular nearly, the anterior angles produced into very long spines, 

 and the posterior or caudal extremity furnished with a very long 

 spine lying in the plane of the body, besides another in the same 

 longitudinal plane, arising from below the base of the caudal spine, 

 and reflexed downward and backward with a curve. 



In fig. 9 a, the mouth is distinctly a moveable trunk, as represented 

 in fig. 96. There is a single eye. The number of appendages is 

 six, as in the young Cyclopoidea. Two of these appendages are 

 antennary, as they are situated anterior to the mouth. The next two 

 may correspond to the mandibles, maxillae, or the first pair of legs of 

 Caligus, we have not determined to which of these organs; the follow- 

 ing two are subprehensile, and probably represent the prehensile pair 

 of legs — the second in Caligus (or first in the Cyclopoids) . 



The first pair (normally the second antennae) is four-jointed, as 

 long as the body exclusive of the caudal spines, and furnished with 

 setse. It projects directly forward. The second pair is still longer 

 and has much longer plumose setae, one or two proceeding from each 

 of seven small joints terminating the organ. The third pair is rather 

 short, and has three joints, besides a claw or moveable finger. The 

 buccal trunk is quite long, and pointed behind. The caudal spine is 

 five or six times as long as the body, and the inferior caudal about 

 one-half the other. 



This animal was taken east of the entrance of the Straits of Sunda, 

 on the 5th of March, 1842. 



In figure 10, the six appendages are shorter, and the second and 

 third pairs are two-branched. The antennae project laterally and are 

 four-jointed, the joints nearly equal in length. The second pair is 

 six-jointed, and a little longer than the antennae ; and at apex there 

 are a few setae as long as the leg. From the second joint behind 

 there is a second branch, consisting of about seven short joints, and 

 furnished with long setae. The third pair has two nearly equal 

 branches on a two-jointed base, each consisting of five joints, the first ol 

 the joints oblong, the others short. Both branches are setigerous, but 

 the posterior has quite long setae, reaching as far back as the caudal 

 spines. No siphon mouth was detected. The two caudal spines 

 are about equal in length ; the spines of the anterior angles pass off 



