HYPERIDEA. 



1003 



process, stout and subcorneous, forming an elongate apex to the basal 

 portion. The inner pair have a two-jointed base, bearing an inner 

 oblong lamella sharply dentated along an oblique summit, and also a 

 two-jointed branch, the second joint of which is the longer, and has a 

 few slender short spines at apex. 



The antennae are very long, the superior rather longer than the 

 body, and the inferior somewhat longer than the superior. The supe- 

 rior have a three-jointed base, with a flagellum which is very long and 

 slender. The base is geniculate at the first articulation. The third 

 joint is longest, and has a prominent ridge below, which is densely 

 hairy. The first joints of the flagellum are very short. 



The two anterior pairs of legs are similar. Both terminate in an 

 oblong extremity, with a subulate apex, which is most slender and 

 longest in the second pair. Only four joints were distinguished 

 besides the straight claw which forms the apex. 



In the third and fourth pairs the claw is more than half the length 

 of the preceding joint, and is but little curved. The fifth and sixth 

 pairs have the second and third joints very short. In the fifth pair, 

 the third is slender and acute behind; the teeth of the hand are six 

 in number and rounded; the claw is about half the preceding joint in 

 length. In the sixth pair, the claw is two-thirds the length of the fifth 

 joint or tarsus, and the fifth joint is shorter than the fourth. In the 

 seventh pair, the coxa is nearly as large as in the sixth pair. The rest 

 of the leg is often concealed by being thrown up against the surface 

 of the coxa. The second joint is short; the third long and slender; 

 fourth short ; fifth still shorter and rounded. The abdominal logs 

 consist of a broad nearly quadrate base, and two lanceolate termina- 

 tions. The latter are finely lined transversely, and are thus divided 

 into ten parts ; they are furnished with long ciliae. The fourth abdo- 

 minal segment bears a pair of appendages each composed of two oval 

 plates, the inner quite broad ; they extend backward beyond the 

 extremity of the abdomen. The appendages to the fifth segment 

 consist each of a single large oval plate, which extends farther than 

 the preceding. None of these plates are ciliated. 



This animal darts through the water with extreme rapidity. When 

 at rest, it lies with the six posterior coxae folded across the venter. 



Several individuals were obtained, and one # of them, cut open 

 between the third and fourth segments of the thorax, was found to 



