ncio and rare British Crustacea. 5 



posed of three nearly equal joints, are armed with moderately 

 long marginal spines, the outer margins of all the joints being 

 also fringed with cilia (fig. 7). In the next three pairs the 

 inner branches, which are also composed of two subequal 

 joints, are much shorter than the outer branches; the outer 

 three-jointed branches are elongate, and the principal terminal 

 seta in both branches is very long and slender (fig. 8). In 

 the fifth pair the inner portion of the basal joint is broadly 

 subtriangular and bears about six elongate seise of unequal 

 leno-th round the apex ; the secondary joint is_ broadly ovate 

 and furnished with two setse on the outer margin and three at 

 the end, the middle one of the terminal three is extremely 

 long and slender, the inner margin is ciliated {{\ir. 11). 

 Caudal stylets about equal in length to the last abdominal 

 segment (fig. 13). 



The male antennules form powerful grasping-organs. The 

 second pair of swimming- feet differ somewhat from those of 

 the female in that the first joint of the inner branches is armed 

 with curved tooth-like processes, as shown in the drawing, 

 and the marginal spines of the first and second joints of the 

 outer branches are much stouter than those of the same joint 

 in the female (fig. 9). The end-joint of the inner branches 

 of the third pair in the male terminates in two moderately 

 long and slightly curved processes, which are of nearly equal 

 length ; a small plumose seta also springs from near the base 

 of the terminal processes (fig. 10). The male fifth pair are 

 small, the inner produced part bears two stout, moderately 

 long, and spiniform terminal setse; the secondary joint is 

 furnished with five setai arranged as shown by the drawing 

 (fig. 12). The first abdominal segment is furnished at the 

 outer distal angle on the ventral aspect with three setae 



(fig. 12a). 



Habitat. Brough Loch, Island of Yell, Shetland. _ 

 EemarJcs. This species somewhat resembles OpMocamptus 

 Irevipes (G. O. Sars), but in that species the antennules are 

 seven-jointed, the end-joint of the inner branches is shorter 

 than, but nearly as stout as, the first joint, and the secondary 

 joint' of the fifth pair is considerably narrower; there is also 

 some difference in the structure of the mandible and in the 

 length of the caudal stylets. It is interesting, however, to 

 observe an oval pellucid area on the dorsal surface of the 

 cephalic segment, similar to that shown in the drawing of 

 OpMocamptus hrevipes by Herr Al. Mrazek*. As we do not 



* " Beitrao- zur Kenntuiss der Harpacticidenfauna des Siisswas^ers," 

 Zoolopisclie Juhrbucher, siebenter Biu.d, p. 116, pi. v. fig. C6, pi. vi. 

 figs. 67-7U. 



