14 NORTH AMERICAN ANOPLURA 



is sharply distinguished from all the other species of Polyplax by the 

 ear-like projections on the temporal margins of the head, by the large 

 thorax and the enormously enlarged coxae of the posterior pair of legs. 

 In the bi-partite character of the tergites and sternites of the abdomen 

 and the presence of a projection on the third antennal joint of the male, 

 it agrees very well with the other species of the genus. 



Description of the Female. — Length 1.2 mm., length of head .22 

 mm., width of head .14 mm., width of thorax .25 mm., width of abdomen 

 .4 mm. 



Head but little longer than wide, having its greatest width across 

 the temporal angles altho the width across the anterior margin is nearly 

 as great. Anterior margin nearly straight, with a very slightly project- 

 ing median portion. Lateral margins of the forehead straight and nearly 

 parallel, the temporal angles very inconspicuous. Temporal margins con- 

 verging slightly in a smooth curve, meeting the slightly convex occipital 

 margin without a perceptible angle. Just behind the antennae and slight- 

 ly in from the temporal margin there rises on each side a small, rounded, 

 ear-like flap which extends slightly beyond the margin and at the base 

 of which there are a very short, stout spine and a slender hair close to- 

 gether. Across the forehead a broad, chitinized area which extends back 

 nearly to the base of the antennae. Anterior margin with a few short 

 hairs and a transverse row of four very small hairs just in front of the 

 antennae. Antennae set very close to the anterior margin of the head, 

 the first segment very broad, occupying nearly a third of the length of 

 the head, and slightly broader than long. Second segment much more 

 slender, but nearly as long as the first and attached close to the posterior 

 margin of the latter. Third, fourth and fifth segments sub-equal, much 

 shorter than the second. 



Thorax very large, much wider than the head and about as long, 

 with lateral margins rounding. Anterior margin with a shallow V-shaped 

 notch, posterior margin deeply concave. Mesothorax with a pair of 

 hairs on the posterior margin, just inside the spiracles. Metathorax 

 nearly divided into two parts by the concavity in the posterior margin. 

 First pair of legs small with slender claw ; second pair larger, with heav- 

 ier claw, slender femur and with the coxae projecting slightly beyond the 

 lateral margin of the thorax; third pair very large, with long slender 

 femur, and with the coxae enormously enlarged and projecting far 

 beyond the margin of the thorax. Sternal plate large, irregularly 

 hexagonal, with the anterior margin slightly convex and longer than 

 the posterior margin, which is slightly concave. Abdomen elongated 



