A NEW TYPE OF AMPHIPODA. 125 



wliich is somewhat thickened in the proximal half, measures 

 almost one half of the whole antennula, while the two distal 

 joints are subequal in length ; all three joints with a few sub- 

 apical setae. The ilagellum consists, as in I. abyssi, of four joints 

 (fig. 23), but the second joint is as long as the first, and all joints, 

 especially the third, are considerably thicker ; the normal setae 

 as in the preceding form. Three olfactory setae are also found 

 in I. littoralis, but those on the second and the fourth joint are 

 considerably shorter than that on the third joint, and the last- 

 named seta is a good deal longer than its joint. The accessory 

 flagellum (fig. 23) nearly as in I. ahyssi, but a little thicker and 

 reaching almost to the end of the second joint of the other 

 flagellum. 



Antennce (fig. 22). — These are somewhat shorter than the 

 antennulae, considerably thicker than in I. ahyssi, and differing 

 in some other particulars. The peduncle is four times as long 

 as the flagellum ; of its three distal joints the intermediate 

 one is considerably longer and a little thicker than the pre- 

 ceding joint, which is a little longer and considerably thicker 

 than the terminal one. The flagellum consists, as in I. ahyssi, 

 of five joints, and it decreases gradually in thickness from the 

 base to the end ; the four proximal joints are subequal in length, 

 while the fifth is very small. The antennae possess more setae 

 than in I. ahyssi, but their arrangement and length are shown 

 in the figure. 



Mouth. — I have not separated the appendages by dissection, 

 but a view from the side did not present any difference worth 

 mentioning from the preceding species. 



Mrst Pair of Tlioyacic Legs (fig. 22). — In the main similar to 

 the same pair of I. ahyssi, but presenting yet some specific 

 characters. The first joint is considerably larger than in the 

 other species, anteriorly produced in a triangular plate ter- 

 minating in a seta. The hand is considerably longer than the 

 head, two and a half times longer than deep ; the anterior 

 margin is rather strongly convex ; the apparent posterior margin 

 as a whole moderately convex ; the palm is only a little longer 

 than the real posterior margin and marked ofi" from it by a small 

 spiniform process. The proximal part of the palm has a rather 

 long and thick marginal spine, and on each side of this a small 

 spine (fig. 24) originating from the inner side near the margin. 

 The sixth and seventh joints with the claw as in /. ahyssi. 



