106 NEOTROPICAL PSELAPHIDAE 



a rounded median lobe which fits into a ventral incisure of the posterior mar- 

 gin of the fifth tergite. Fifth sternite with a minute tubercle at middle of 

 apical margin. 



Prosternum with the apical margin serrato-dentate ; medianly gibbous, 

 with the posterior portion of the gibbous area fonning a short carinated ele- 

 vation between the lateral prosternal foveae which are well-developed anteriad 

 of each coxa. No entire median longitudinal carina. 



Mesostemum not carinated medianly, flat and shining. 



Metasternum medianly tumid, with a short sulcoid area at extreme 

 posterior fifth; long, as long as third and fourth sternites united. 



Anterior coxae short, conical; middle coxae subcontiguous, the meso- and 

 metasternum discernible between them as narrow, flat, acute extensions; 

 posterior coxae contiguous, shortly conical. Legs simple, with short three- 

 segmented, euplectine tarsi, the first tarsomere very small, the next two much 

 larger; second tarsomere very much larger than the third, the third bearing 

 a single claw. 



The paratypes agree with the type, save that the median discal fovea of 

 the pronotum is more linear and longer; in one paratype the elytra have the 

 fourth (most lateral) basal fovea much smaller than the other three. From a 

 slide mount of a paratype the following morphological additions can be added: 

 (1) the sternal foveae are very well developed; in addition to the lateral 

 prosternal foveae noted previously, the meso- and metasternum have foveae II, 

 III, IV, and V paired and present. II are large, with a bifurcated whorled 

 lumen, one arm of which penetrates the prepectoid and one arm the mesoster- 

 num proper. Ill are small, with a single whorled lumen, one on each side of a 

 median longitudinal carina of the prepectoid. IV are relatively as large as 

 any I have encountered, and typically located, that is, at the lateral angle 

 of each middle coxal cavity, at the union of five sclerotic areas (mesosternum, 

 mesoepisternum, mesoepimeron, and metasternum). VI are small, one in the 

 center of the posterior margin of each middle coxal cavity. (2) Each of the 

 elytra has three asetose pores. These appear as very clear, perfectly circular 

 areas in strong relief against the yellow integument. They appear to be sensory, 

 and, although they have no relation to the setal punctures, are of almost the 

 same size. Two of these pores lie on the disc at the apical fourth. The third 

 lies in the basal third, posterior to a line drawn between the fourth and third 

 basal foveae. (3) There appears to be a peculiar mechanism between the 

 inner face of the elytra and the sides of the invisible first tergite. In life this 

 tergite, which is membranous, is tucked beneath the elytra. In the cleared speci- 

 men, there are about twelve short oblique striae on the lateral face (pleurite?) 

 of this membranous segment. In apposition are about eight transverse carinae 

 on the internal face of the elytron, near its apical external angle. Such a 

 mechanism suggests the possibility of a stridulatory mechanism, but no further 

 data concerning the possible function of this area are at hand. 



Described on four females, collected by the author, beneath the bark of logs 

 on Barro Colorado Island, Gatun Lake, Panama Canal Zone, as follows: July 



