NORTH AMERICAN SPECIES OF THE GENUS ATAX 219 



niai'gin two-thirds the way towards the tip, short, and with a slender 

 spine, the third at the distal margin short and inconspicuous. r >, broad, 

 laterally quadrate in outline, with the ventral distal angle produced and 

 on the distal margin two slender, strongly curved claws, one near the ex- 

 tensor margin, the other about in the median line. 



Epimera large, covering most of the under surface of the body and 

 with a very narrow space between II and III and between those of oppo- 

 site sides. I, rather broad, with parallel margins, the anterior margin 

 concave, the posterior slightly convex. II, slightly broader than I and 

 with its posterior margin quite convex and forming with the inner end of 

 I a continuous curve. Line of separation between III and IV distinct one- 

 half the way in from the lateral margin and one-fourth the distance from 

 the anterior towards the posterior margin of the plate formed by the two. 

 Anterior margin of III concave and anterior internal angle projecting. 

 Posterior margin of IV strongly convex, indistinctly angulated, and pro- 

 duced backward to a point even with the genital area, which thus lies in 

 an angle between the last two epimera. Lateral margin deeply excavated 

 between the points of articulation of legs III and IV and opposite the 

 division between the corresponding epimera. The surface of the body 

 between the four groups of epimei-a is thickened and so to a certain ex- 

 tent all are fused into one mass. The surface of all the epimera is 

 marked, as is the rest of the body surface, by a system of lines cutting it 

 up into small hexagonal areas, and the same is true of the maxillary 

 plates. 



Legs.— In the male, very short and comparatively thick, the last 

 especially so. I averages one-seventh shorter than the body and is 

 shortest of all, III is one-seventh longer than the body, II a sixth longer 

 and IV a fourth longer. Of the individual segments, 1 is shorter, 2 and 3 

 are about equal and next longer; 4 is longest except in IV where 6 is very 

 long, exceeding it and all the others; while in I and II, 6 exceeds 5 and 

 in III the reverse is true. The legs are all moderately well supplied with 

 spines and are not noteworthy except in the case of III, 5 and IV, 4 to 6. 

 The former has at its tip three doubly curved blade-like spines reaching 

 three-fourths the way to the end of 6. Of the latter, IV 4 is compressed 

 laterally through the distal two-fifths of its length and on this compressed 

 portion bears a bunch of six very large spines, placed in two rows on the 

 ventro-anterior surface, and exceeding in length the next segment, while 

 on the posterior surface are about nine spines, of which six are moder- 

 ately stout, while the three distal are very long and slender and reach 

 beyond the distal end of 5 by about one-third its length. 5 is short, at its 

 base narrower than 4, tapering toward the tip, with two very heavy, 

 curved blunt spines on the extensor surface and a row of spines along the 

 flexor side, and a bunch of fine hairs at the distal end, while 6 is very 

 slender and rather long. All the claws are strongly bent and bifid, with an 

 accessory tip on the convex side short and inconspicuous and ending at a 

 distance from the end equal to one-sixth the whole length of the claw. 



