20 



THE VOYAGE OF H.M.S. CHALLENGER. 



There is no articulated scale on the outer antenna such as is found in Janira. 



The uropoda (fig. 10) are of considerable size compared with what is usual in this genu- ; 

 the basal joint is wide ; the two rami are narrow but of about equal length with the basal 

 piece; the inner ramus is rather longer as well as thicker than the outer. Both are 

 furnished with numerous long stiff hairs. 



Eock Pools, Kerguelen. 



Jseropsis, Kohler. 

 Jxro2)s>'s, Kohler, Ann. d. Sci. Nat., st'r. 6, t. xix. No. 1. 



M. Kohler has described a little Isopod from the Island of Sark, which bears man) 

 resemblances to Jsera, but which he regards as being the type of a new genus ; the name 

 employed by him is significant of the affinities of the Isopod. The genei'al form of the 

 body is that of Jsera, with which it also agrees in the rudimentary nature of the terminal 

 abdominal limbs of the uropoda. The main structural feature which distinguishes 

 Jseropsis from Jsera is to be found in the antennae, which instead of being long and 

 slender with a well-developed flagellum, are extremely small with a rudimentary 

 flagellum. The single species, which is very minute, measuring only from 2 to 3 mm., is 

 named Jseropsis brevicornis. 



A species obtained at Marion Island during the voyage of the Challenger appears to 

 me to be referable to this genus, but to be specifically different from J&rojisis brevi- 

 cornis. The descrbption of this new species is as follows : — 



Jseropsis marionis, F. E. Beddard (PI. I. figs. 11-15 ; PI. II. fig. 1). 



Jseropsis mariunis, F. E. Beddard, Proc. Zool. Soc. Lond., 1886, pt. i. p. 105. 



The single specimen of this species, from dredge-mud off Marion Island (100 

 fathoms), differs very distinctly from the other species of the genus. 



The specimen is a male, and measures nearly 4 mm. in length. 



The head is large and roughly quadrangular in outline; the anterior margin is prolonged 

 between the antennae into a rostrum which is deeply notched ; the eyes are of fair size 

 (I counted seventeen crystalline cones) and dorsal in position ; the lateral margins of the 

 head, which are very much bent down, are serrate. 



The general shape of the body is cylindrical, the diameter being everywhere approxi- 

 mately equal ; the species is also marked by the great convexity of the middle of the 

 body. 



The head is about as long as the first two segments of the thorax taken together; the 

 latter are subequal, the third is slightly shorter, the fourth and fifth subequal and very 

 much shorter again ; the two last segments of the thorax are quite as long as the two 



