North American Centropagidae. 241 



first, and rather more than twice as long as wide ; armed on 

 the outer margin with a few hairs and a moderately stout 

 plumose seta. Third segment about as wide as the second, 

 with margins sulcate ; outer margin armed with two stout 

 plumose setae, the proximal third with a few fine hairs ; inner 

 margin and apex each armed with two stout plumose seta?. 



First basal segment of left fifth leg subquadrate, having 

 near the inner apical angle a large tubercle bearing a few 

 rather long hairs. Second basal segment somewhat narrower 

 than the preceding and not twice as long as wide ; armed at 

 the outer apical angle with a prominent hyaline process. 

 First segment of outer ramus subquadrate, rather more than 

 twice as long as wide ; armed on the inner margin, at the be- 

 ginning of the distal third, with a small process provided with 

 hairs, and at the outer apical angle with a short blunt spine 

 and a long stout movable spine serrate on the inner. margin. 

 Second and third segments ankylosed, forming one very long 

 narrow segment, slightly narrower than the first and more 

 than twice as long ; provided for the greater part of the inner 

 margin with hairs, and armed on the outer margin with three 

 spines, the upper two similar to the larger one of the preced- 

 ing segment, the third sometimes serrate on both margins ; 

 provided at the inner apical angle with a narrow digitiform 

 process about half as long as the segment itself and serrate 

 on the outer margin. 



Inner ramus of the left fifth leg very similar in every re- 

 spect to that of the right leg. 



First basal segment of fifth leg of female of the ordinary 

 form. Second basal segment about as wide as the first and 

 barely twice as long as w r ide ; outer half of the distal margin 

 produced in the form of an irregularly triangular flap extend- 

 ing over the margin of the first segment of the outer ramus. 

 First segment of outer ramus quadrate, about twice as long 

 as wide ; armed at the outer apical angle with a stout spine 

 serrate on the inner margin. Second segment somewhat nar- 

 rower than the first and not quite twice as long as wide ; 

 armed with hairs on both margins and at the outer apical 

 angle with one short spine and a longer, stouter one serrate 



