BATRISINI 221 



which is very broad and deepens apically, the apical margin abruptly erected 

 to form a posterior wall of the depression and this apical margin medianly 

 slightly concave; basal-external angles of depression subserrately elevated 

 into three or four minute blackened obtuse denticles, each denticle bearing a 

 long coarse, flavous, decumbent seta which is directed medio-posteriorly for 

 one-third or more of the depression. Sixth (last) sternite minute, transversely 

 fusiform, granulate-punctate, and lies between the median apical margins of 

 the last tergite and next to last sternite. 



Intermediate trochanters conspicuously abnormal, with the ventral face 

 flat and ovate, this surface crowded with short, uniform setae and in addition 

 a single, very long seta which arises from the anterior margin of the pad 

 (examination of the numerous male paratypes, both dry and microscope slide- 

 mounts, attests to the complete constancy of this single erect seta set in the 

 pad of short setae) . Anterior and posterior trochanters, all femora and anterior 

 tibiae simple. Intermediate and posterior tibiae with a strong uncus near apex. 

 Tarsi normal for tribe. 



Allotype Female. Similar to holotype save that (1) eyes are slightly 

 smaller and tempora slightly longer; (2) occipital carina not as strongly 

 formed; (3) vertex simple, semicircularly impressed between antennal tubercles, 

 with an evenly declivous front which lacks teeth and tubercle; (4) clypeus 

 simple, declivous, evenly convex; (5) antennae simple; (6) first tergite 

 relatively shorter; (7) only five fully visible sternites, of which the last is 

 large, distinctly longer than preceding three united, semilunar in outline with 

 a concave apical margin; (8) intermediate trochanters simple; (9) tibiae not 

 apically armed. 



Described on 15 specimens, all collected on Barro Colorado Island, Gatun 

 Lake, Panama Canal Zone. Male paratype (July 7, 1936) ; three male para- 

 types (July 15, 1936) ; male paratype (July 16, 1936) ; male holotype (July 

 22, 1936) ; three male paratypes (July 24, 1936) ; male paratype (July 29, 

 1936) all collected at light at night after 9 P.M. and before midnight, and 

 all collected by the author. Two male paratypes (July 17, 1938) , one male and 

 one female paratype (July 19, 1938) and allotype female (July 23, 1938) all 

 collected from leaf mold of the rain forest floor by Dr. Eliot Williams. 



From these data it should be noted that although ten were taken at light 

 at night, only five were collected during the day. Of these taken at light all 

 were males, but the diurnal catch was of nearly equal sex ratio (3 males, 2 

 females). This is either coincidence or an indication that the males fly to 

 light more than females. 



Second, it seems clear that the species is nocturnal. This is a general rule 

 for the family but heretofore has lacked definite substantiation. Thus careful, 

 quantitative quadrat samples of the forest leaf mold discovered sabomba in 

 the floor by day and not by night; the same species, in the same locality, was 

 taken on the wing only after dusk. For a full statement of the analysis the 

 work of Williams (1941) should be examined. 



Third, a male (July 17, 1938) and a female (July 19, 1938) had evidently 



