1908.] GENUS OF AMPHIPOD CRUSTACEA. 395 



In the yo%mg the peduncle is much longer in proj ortion, with 

 one seta on the outer side and two coupling- spines on the inner. 

 The rami are very little longer than the peduncle ; the oider 

 ramus is composed of 4 joints, the 1st nearly three times as long as 

 the other three together, each joint provided with two long plumose 

 setse ; the inner ramus has 3 joints, the 1st four times the length 

 of the other two together, two plumose setfe to each joint, and one 

 large cleft spine on the fii^st. 



Vrovohx.^ Adult (PL XXI. figs. 9, 10, 11,13; cf. also fig. 14), 

 The apices of the 1st uropods reach considerably beyond the 

 peduncles of the 3rd ; those of the 2nd and 3rd pairs are on a 

 level. 



The peduncle of the \st uropocl is broad and long, equal to the 

 outer ramus in length, with one small seta on its outer margin, 

 and ten large, strong spines on the inner edge. The rami are 

 broadly lanceolate, curved, the outer being the shorter of the two. 

 The inner ramus has both margins serrated, with three spines on 

 the inner one ; the outer ramus bears six minute sensory setules 

 (fig. 11) deeply indented in its upper margin, the distal half of 

 wdiich is serrated, as is also the under margin. 



The rami of the 2nd tiropod are subequal, longer than the 

 peduncle and slightly curved. The peduncle hears one small 

 spine on the inner angle. The upper margin of the outer ramus 

 is beset with five minute setules, no sensations, all the other 

 mai'gins finely serrated. 



The peduncle of the ^rd uropod is short, wider than long, the 

 rami twice its length, the outer one bi-articulate. The outer 

 margins of both rami are plain, the inner edges serrated ; the 

 small 2nd joint of the outer ramus having 12 or 13 fine 

 seri'ations. 



For the young, see PI. XXI. figs. 12, 15, 16. The outer margin 

 of the outer ramus of the 1st and 2nd uropods is deeply notched 

 near the apex. In this notch, set as it were in a little pocket, is 

 a large sensory seta, similar io the sensory setule of the adult, but 

 on a much larger scale (fig'. 12). 



TEJ.SON. —Adadt (PI. XVII. fig. 13, PI. XXI. fig. 17). Rounded 

 anteriorly, narrowing posteriorly, longer than the peduncle of the 

 3i-d uropod, and almost as broad as long. The apex is obtusely 

 truncated, distinctly emarginate, tipped with two setules. It 

 has four transverse rows of spinules clorsally, as described for 

 T. nicceense, and six of the tufted setules. (For arrangement and 

 detail, see PI. XYII. fig. 13 ; cf. fig. 11.) 



In the immature (PI. XXI. fig. 18) and young forms (fig. 15) 

 the telson is incised for about one fifth of its length, with 

 the apices rounded. 



III. General Remarks. 



The Norwegian form of this animal when first discovered was 

 considered of sufficient importance to rank as one of the principal 



