190 NEOTROPICAL PSELAPHIDAE 



annular constriction at base of swelling; length 1.5 mm 



arthriticum 



Intermediate femora otherwise modified 11 



11. Intermediate femora greatly swollen, deeply emarginate and im- 

 pressed; basal edge of emargination prolonged into a tooth in the 

 same plane, apical margin continued within the emargination on 

 the outer edge by a transparent lamella; bottom of emargination 

 provided with an oblique lamella not connected with the sides; 

 1 .2 mm. long complicatum 



This key covers the species of the sixth group with the exception of 

 curticorne (Schaufuss) from Yucatan, Mexico. This species, unknown to me, 

 is said by Raffray (1904, p. 189) to be close to arthriticum Raffray, but 

 differs from Raffray's species in an entirely different structure of the male 

 intermediate femora and much larger third, fourth and fifth antennal seg- 

 ments. 



Decarthron chichion new species 



Holotype Male. Measurements: Head 0.2 x 0.3 mm. through eyes; pro- 

 notum 0.268 x 0.3 mm.; elytra 0.4 x 0.57 mm.; abdomen 0.28 x 0.56 mm. from 

 a strictly vertical view; total length 1.3 mm.; greatest width 0.57 mm. (PI. 

 VI, XVI) 



Light reddish-brown, shining, integument clothed with moderately long, 

 orange, subdecumbent pubescence; head, pronotum and abdomen lightly 

 punctulate, elytra more heavily punctate (the elytral integument is thrown 

 into semitransverse subscabroid wrinkles in one of the paratypes, probably a 

 consequence of preservation too soon after pupation) . 



Head with large, prominent eyes (0.107 long x 0.067 mm. wide from a 

 vertical view) composed of about 32 very convex, coarse facets; the eye is 

 sharply reniform from a lateral view. Vertex not medianly carinate but trans- 

 versely swollen posteriorly and flattened anteriorly; with two free, nude, minute 

 vertexal foveae, each smaller than an ocular facet but set in the bottom of a 

 gently sloping depression so that they appear superficially larger, each fovea 

 nearer an eye than to each other and on a line with the third transverse row of 

 ocular facets; each side of vertex with a short, subarcuate incision at base of 

 antennal area. Front medianly and triangularly truncate between antennal 

 bases and then dropping abruptly in an anteriorly oblique plane as a narrow, 

 suboblong with nearly parallel sides, to the anterior margin of the epistome. 

 This declivous surface roughly punctate or subscabroid. Apical margin of 

 labrum concave. Left mandible crossed dorsal to right mandible. Ventral sur- 

 face of head with a large, sharply-defined, deep ovoid fossa (described from 

 male paratype). 



Antennae ten-segmented, distantly inserted beneath antero-lateral angles 

 of head. The fourth, seventh, and eighth segments very abnormally formed 



