North American Centropagidce. 253 



ones. Third segment slightly shorter than the preceding; 

 process very simple, small and inconspicuous, bluntly pointed, 

 extending almost straight backward ; armed on outer margin, 

 near the tip, with a slight, blunt protuberance. Fourth seg- 

 ment unarmed, about half the length of the first. Fifth 

 segment about as long as the fourth ; armed with a narrow 

 triangular plate, broadest anteriorly and bluntly rounded at 

 the apex. Dextral margins of the fourth and fifth segments 

 tuberculate. Furcal rami about as in the female. 



Antenna? 25-segmented, extending almost to the base of the 

 furca. Eight antenna of the male geniculate between the 

 18th and 19th segments ; segments preceding the geniculation 

 slightly or not at all swollen. 



Eight fifth leg of the male three-segmented. First seg- 

 ment irregular in form, about twice as long as wide, armed 

 on the outer margin, near the distal angle, with the usual deli- 

 cate hair ; inner margin provided with a curious, smooth, 

 bluntly-pointed hook-like process extending downward almost 

 parallel to the margin. Second segment irregular, about 

 twice as long as wide ; outer margin smoothly convex, armed 

 near the distal angle with a small spine ; outline of inner 

 margin sinuous. Third segment long and narrow, with a 

 broad basal portion about half as wide as the segment is long ; 

 curved inward slightly at the tip and armed here, on the outer 

 margin, with a minute spine. 



First segment of left fifth leg with a subquadrate main por- 

 tion produced on the inner margin into a long, smooth broad 

 hook but slightly curved ; armed at the outer distal angle 

 with the usual hair. Second segment somewhat narrower 

 than the first, subquadrate, about twice as long as wide ; outer 

 distal angle armed with a small sharp spine; inner margin 

 sometimes with indications of minute teeth or serrations at 

 about the middle. Third segment curved inward slightly, 

 about as broad as the second and fully four times as long as 

 broad ; armed on the outer margin with four rather small 

 sharp spines, the first at about the middle, the second midway 

 between this and the apex of the segment, the other two near 

 the apex and nearer together than the upper ones ; armed on 



