172 NEOTROPICAL PSELAPHIDAE 



slightly tumid with a deep, subtriangular excavation in basal half occupying 

 one-sixth of the segmental width. 



Mesostemum advanced between the distant intermediate coxae as a sub- 

 truncate plate, this plate densely pubescent. 



Metasternum slightly longer than first visible sternite, evenly and simply 

 convex, posteriorly truncate between the very widely separated posterior coxae. 

 Sternal foveae IV well developed, one at each lateral angle of an intermediate 

 coxal cavity, the mesial wall of the fovea recessed by a longitudinally arcuate 

 carina which extends from this point posteriorly for almost one-half the meta- 

 sternal length. The metasternum medianly advanced between the intermediate 

 coxae, meeting the mesosternal process, and like the latter pubescent in this re- 

 stricted area. This pubescent intercoxal region is elevated above the plane of 

 the metasternum and the paired sternal foveae VI lie just posterior to the ele- 

 vation. The posterior walls of the intermediate coxal cavities are strongly 

 beaded, this bead forming the anterior margin of the metasternum at this point 

 and continuous with the intercoxal extension mesially and continuous with the 

 longitudinal metasternal carina laterally. 



Anterior femora strongly inflated; intermediate and posterior femora not 

 inflated. Anterior and intermediate tibiae normal ; posterior tibiae thickened in 

 apical half and strongly arcuate internally. Trochanters and coxae not armed. 

 Anterior tarsi with second tarsomere dilated and flattened, the ventral face pro- 

 vided with a brush of short oblique setae ; intermediate and posterior tarsi nor- 

 mally developed and slender. 



Examination of a male paratype, cleared and mounted in balsam, reveals 

 additional structural details not appreciable in a triangle mount: (1) The 

 labrum is seen to have two minute acute teeth which arise from the ventral sur- 

 face and extend anteriorly slightly beyond the distal margin; (2) The obliquely 

 truncate tooth at external base of each mandible has several convergent pore 

 canals which extend into the integument as fine invaginations. These canals sug- 

 gest a sensory function for this mandibular boss; (3) On each side of the head, 

 between the antennal base and the eye, the integument is invaginated obliquely 

 to form a long subpyramidal tube. This air-filled tube courses beneath the ver- 

 texal integument to end blindly near each vertexal fovea. As far as I know, 

 this tubular extension is unique. It does not have any discernible connection 

 with the vertexal fovea, nor with the arm of the supratentorium which connects 

 the floor of the vertexal fovea with the floor of the gular fovea of each side; 



(4) The gular foveae are two in number and widely separated, one on each side 

 of the extreme base of the longitudinal median carina of the ventral surface of 

 the head, and clearly connected with the vertexal foveae by the supratentorium ; 



(5) The circular, flat-topped, drum-shaped boss of the eleventh antennal seg- 

 ment is seen to have thin walls and apparently extends deeply into the sub- 

 stance of this segment; (6) The four basal elytral foveae are seen as minute, 

 deep cylindrical foveae penetrating the elytral integument; (7) The true first 

 sternite of other tribes is visible as a narrow, wide membranous sclerite between 

 the posterior coxae, and wholly covered by the metasternum; (8) The penis is 



