20 PROCEEDINGS OF THE NATIONAL MUSEUM vol.69 



Genotype. — Tachardiohius nigricans^ new species. 



Female. — Head rather thick frontooccipitally, about as long as 

 wide, the face abruptly inflexed but the frons not prominent; dorsal 

 surface of the head well rounded at the sides, depressed medially; 

 in frontal view the outline is subcircular, well rounded on the sides, 

 depressed above; in side view the outline is triangular, with the 

 dorsal side not more than one-half as long as either of the other 

 sides, the facial side straight, the other two sides slightly bulging. 

 Occiput moderately concave, its dorsal margin rather acute; eyes 

 rather small, strongly convex, a little longer than wide, the longer 

 axis oblique to the longitudinal axis of the head; frontovertex com- 

 prising more than one-third of the total width of head, a little longer 

 than wide, its anterior margin forming an angle of about 90° with 

 the face and deeply notched medially; ocelli large, arranged in a 

 nearly equilateral triangle, the posterior pair somewhat less than 

 their own diameter from the eye margins and about as far from the 

 occipital margin; cheeks broad, convex, and a little shorter than 

 the transverse diameter of the eyes, the genal suture obsolete; face 

 very flat, extending well upward between the eyes, the scrobes in 

 the form of narrow, deep sulci which meet in an angle above and 

 notch the anterior margin of the frons; the oral margin broadly 

 and rather deeply emarginate, exposing the labrum, which bears a 

 rather dense fringe of longish setae. 



Antennae inserted rather far apart, about halfway between the 

 oral margin and the ocular line; scape rather long, linear, and a 

 little compressed, reaching slightly beyond the plane of the frons, 

 and including the radicle slightly longer than the pedicel and first 

 four funicle joints combined; pedicel slightly less than twice as 

 long as thick, a little shorter than the first two funicle joints com- 

 bined ; flagellum moderately clavate, the funicle six-jointed, the first 

 joint about one-third longer than thick, the sixth joint as wide as 

 long; club three-jointed, oval, wider than the funicle and a little 

 shorter than three preceding joints combined. 



Mandibles with a small acute ventral tooth and a moderately 

 broad inner truncation, the apex, however, not in the same plane 

 with the expansion of the base, as is usual in cases with this type 

 of dentition. Maxillary palpi short and slender, four- jointed, the 

 two middle joints distinctly thicker, the second as long as wide, the 

 first and third about one-half longer than the second, the fourth fully 

 twice as long; labial palpi very short, three- jointed, the basal joint 

 about one-half longer than thick, the last two joints very short and 

 subequal. 



Thorax robust, strongly convex above, about one-third longer than 

 wide; pronotum strongly arcuate; mesoscutum about twice as wide 

 as long; axillae short, transverse, and acutely meeting medially; 



