CHAMBERLIN: HENICOPIDAE or AMERICA NORTH OF MEXICO. 21 



Antennae long; clearly more than half the length of the body, 

 ordinarily reaching the ninth segment. Articles 36; of which the first 

 two are longest and the third shortest, the others increasing gradually 

 from the third distad and commonly showing a tendency for single 

 longer articles to alternate with pairs of somewhat shorter ones. Sub- 

 densely clothed with long bristles. 



Organ of Tomosvary rather large, circular; on ventral border of 

 head immediately in front of level of greatest width. (Plate 4, fig. 1). 



Major dorsal scuta, excepting the sixth, with the caudal margin 

 convexly rounding at corners and mesally weakly incurved; caudal 

 margin of sixth plate slightly convex a little bent cephalad toward 

 ends. Minor scuta have the caudal margin straight; the caudal 

 corners of the second, fourth and sixth very shortly obliquely excised, 

 at least on one side; the caudal margin of the ninth and eleventh, 

 especially of the former, bent forwards at ends nearly always more 

 strongly on one side than on the other, or else on one side only; caudal 

 margin of thirteenth a little incurved mesally. Tergites well arched; 

 marked with several pairs of somewhat irregular longitudinal sulci 

 of which one a little each side of middle and mostly curving ectad at 

 its middle and one or two each side farther toward the lateral margin 

 are most constant and most sharply impressed; shorter impressions 

 elsewhere largely breaking the surface into short and irregular fine 

 rugae. 



Most ventral plates with a distinct and rather wide transverse 

 depression or furrow at level of legs, this furrow on some anterior 

 segments replaced by two which are often considerably separated; 

 usually several other transverse furrows or sulci which are more dis- 

 tinct on caudal portion of plate. 



Legs all long, the ultimate pair being especially long and slender; 

 anal and penult legs ending in a single claw or the accessory of the 

 latter obsolete, all other legs terminating in three claws. (Plate 3, 

 figs. 8 and 9). 



Coxal pores small and circular; 3, 3, 3, 3-4, 4, 4, 4. 



Gonopods of the female with the claw long, slender, and acute; 

 strongly bent. Basal spines 2+2, acutely conical; the slender distal 

 portion usually blackish. (Plate 3, fig. 10). 



Gonopods of the male long; attenuated from base distad. Distal 

 article ending in an acutely pointed spine. Genital duct opening 

 through a distinctly protruding, broadly rounded process. 



Length 10-12 mm. Width of tenth plate 1.3-1.4 mm. 



LOCALITIES. Mississippi (Byram! Canton I). 



