174 



THE VOYAGE OF H.M.S. CHALLENGER. 



The three remaining segments are subequal; the anterior part of the segment is 

 narrow and forms a constricted portion, connecting the segment with the one in front ; 

 the lateral regions are wider posteriorly, and their lateral margin slopes outwards and 

 backwards; the postero-lateral angle of each segment is furnished with a short sharp 

 spine. 



The abdomen is elongated, and slightly wider anteriorly than posteriorly ; it is 

 separated by a constriction from the segment in front. The abdomen terminates 

 posteriorly in an obtusely rounded extremity, in front of which, on each side, is the 



Fig. 2. — Macroslylm lati/rons, n. sp. 



articular surface of the uropoda. The length of the abdomen is about equal to that of 

 the two preceding segments of the thorax. Its lateral margins are smooth. Eyes are 

 completely absent. 



The antennules are articulated close to the antennae on the antero-lateral margin of 

 the head ; the appendages are very short, being about one-half the diameter of the head 

 itself at the point where they are articulated. The basal joint is the stoutest, and there 

 are five joints altogether, of which three may be allowed to the flagellum ; the distal 

 joints are very much more slender than the proximal. The terminal joint bears a single 

 olfactory hair. 



