AMPHIPODA FROM BAY OF BISCAY. 203 



The following notes may be found useful iu supplementing the short 

 account given by Chevreux : — 



Body. Peraeon-segment 7, and pleon-segments 1-4 dorsally ser- 

 rate as in S. liapyracca. Stebbing, to which it bears a strong re- 

 semblance. The number of the serrations differs in the different 

 segments, and occasionally the number on one side of a segment differs 

 from the number on the other side ; each serration has a long fine setule 

 inset. In peraeon-segment 7 the serrations number twenty on the 

 right side of the prominent central tooth and eighteen on the left ; they 

 extend across the segment almost to the posterior angles, each of which 

 is produced into a small tooth with a setule inset above. The 1st 

 pleon-segment has twenty-five serrations, the middle one much the 

 longest ; postero-lateral angles acutely produced, as in the 2nd pleon- 

 segment also. This latter has twenty-one serrations, the middle one 

 again the longest ; five sensory spines inset along the inferior margin 

 of the epimera, which are much dilated anteriorly as well as posteriorly. 

 There are eighteen dorsal serrations on the 3rd pleon-segment, the 

 two middle ones, of unequal length, much longer than the others ; the 

 epimera are considerably dilated inferiorly, the hind margin with seven- 

 teen upturned serrations, each with a setule inset. The 4th pleon- 

 segment has twenty-five of the serrations ; while the 5th carries two 

 or three similar serrations on either side, just above the insertion of the 

 uropods. 



Head. Strongly vaulted in front, equalling the first four peraeon- 

 segments taken together, in length ; rostrum depressed, reaching beyond 

 the middle of the 1st joint of the antenna, sharp-edged, apex very 

 acute ; lateral corners not much produced, truncate. 



Sideplate 1. Front margin lightly curved forward; front angle sub- 

 acute, hind angle rounded ; posterior margin produced proximally as in 

 Sideplate 2 ; inferior margin dilated. Inferior margin of Sideplate 2 

 narrowed and rounded. In Sideplate 3 the truncate portion of the 

 hind margin has a crenulate appearance owing to the insertion of four 

 or five setules. Sideplate 5 not much produced anteriorly, expanded 

 and rounded posteriorly. In Sideplate 6 the anterior portion is hardly 

 developed at all ; the posterior portion is greatly produced downwards 

 with its inferior margin truncate, one serration at the posterior angle. 

 Sideplate 7 also with one tooth posteriorly, as noted by Chevreux. 



Antennae. Superior antenna. 1st joint of the peduncle thick, 

 more than twice as broad as the succeeding joints, with a strongly 

 upcurved apical tooth; 2nd joint nearly as long as the 1st; 3rd 

 not quite three-quarters the length of the 2nd, all carrying ciliated 

 hairs and setae. Primary flagcllnm 15-jointed, witli a long sensory 



