155 



tends anteriorly and upwards about half way to the anterior 

 margin of the segment. The inferior and posterior margins of 

 the Urst to fifth segments of pleon (inclusive) are regularly fringed 

 with long seta?, thickly set on tlie inferior margin but more sparsely 

 placed on the posterior margin. On the inferior margin of the 

 sixth segment the corresponding seta? (about 15 or 16 in number) 

 are short and stout, almost spiniforra, most of them bear 4 or 5 

 pectinations on the posterior edge toward the end of the set*. 

 The projections at the end of the tail piece are thickly covered 

 with setfB of various sizes, some of them thick and spiniform. 



Surface, of body. — In the pereion the sui'face has a crinkled 

 appearance caused by numerous shallow depressions separated by 

 small narrow ridges ; the first segment is smoother than the others 

 and the surface of the head is also smooth. The surface of the 

 pleon with the exception, to some extent, of the dorsal surface is 

 smooth. In the pereion there are a few setaj partially arranged 

 in tufts scattered about on the dorsal surface, and the inferior 

 angles both of the segments and of the epimera usually bear a few 

 short sette. In the pleon, especially in the posterior segments, 

 the dorsal surface is covered with a thick fur of short seta? with 

 some longer scattered setfe as in the pereion, but more numerous. 

 The long setie on the margins of the segments of the pleon have 

 been already mentioned. 



The ground tint of the colour is a light brown and is seen in 

 the appendages, but in the body this ground tint is almost covered 

 with marbled markings of a much darker brown, the lighter colour 

 showing up in more or less rounded patches on the head and here 

 and there on the segments of the pereion. The lateral portions of 

 the pleon are usually darker than the other parts of the body and 

 of a uniform slaty colour. This colour is probably protective — 

 Mr. Helms notes that the animals looked exceedingly like the 

 surrounding earth. 



Ujjper antenna. (Plate xxiii., fig. 2.) — The upper antenna is 

 short, scarcely reaching to the end of the peduncle of the lower 

 antenna, the peduncle apparently consists of three joints, but is not 

 clearly distinguishable from the tlagellum. The first joint is 

 partially hidden by the head, it is longer and broader than the 

 second joint, which is of about the same length as the third, but 

 broader. The flagellum consists of from 5 to 7 joints, the proximal 

 joints usually short, the others longer and swollen, this being most 

 noticeable in the third and fourth joints from the end; the terminal 

 joint is very small and is tipped with a few sette. The swelling 

 of the terminal joints is chiefly confined to the chitinous integu- 

 ment, the central portion containing the muscles <fcc. not being 

 similarly swollen. The setaj on the antenna are few and small ; 

 there are a few on the second and third joints of the peduncle 

 and on some of the joints of the flagellum. On the last four joints 



