274 NEOTROPICAL PSELAPHIDAE 



Abdomen with jBve visible tergites in the length ratio of 3/1.8/1/1/1, simple. 

 Margins as follows: first tergite each side with two parallel, subentire carinae 

 with the internal carina strongly Y-shaped (a rounded cusp of elytral apex 

 fitting into the bifurcation) ; second, third, and fourth tergites each side with a 

 straight, short internal carina and second and third with a rudiment of an ex- 

 ternal carina at base. 



Six stemites in the length ratio of 1.3/1.5/.6/.5/.5/1.2. First sternite visible 

 side to side, separated from second by a deep pubescent trough ; sixth sternite 

 with a suberect, transvesely arcuate, lamelliform carina at middle and one-fifth 

 the segmental length from apical margin. 



Metastemum medianly, longitudinally sulcate. 



Posterior coxae distant, separated by a distance equal to three-fourths the 

 median metastemal length. Legs simple save posterior tibiae. Each posterior 

 tibia thickened in apical half, the thickened portion sharply arcuate. A tuft of 

 long setae at start of arcuation on internal face, and apex with a dense pad of 

 short setae and a stout, arcuate tooth. Tarsi three-segmented; first tarsomere 

 very short, last two relatively long, second longer than third ; third with a long 

 tarsal claw. 



Allotype Female. Similar to holotype save that (1) longitudinal median 

 carina of posterior half of head much longer, extending to a point opposite an- 

 tennal bases; (2) anterior median longitudinal carina not present; (3) sides of 

 head anterior to eye elevated, but in the form of a wide flattened margin, not 

 produced apically as horns, but simply converging between and below antennae 

 as a narrow continuous, carinoid arc; (4) front evenly declivous and entirely 

 simple save for the union of the marginal elevation just noted; (5) clypeus 

 simply declivous; (6) sixth sternite not modified; (7) posterior tibiae slightly 

 arcuate through apical half, without basal tuft and lacking terminal tooth. 



Described on twenty-three specimens, all collected on Barro Colorado 

 Island, Gatun Lake, Panama Canal Zone. One female paratype collected August 

 15, 1935, by Alfred Emerson in nest of the termite, Cornitermes (C.) acignathus 

 walkeri Snyder. Rest collected by the author as follows: Two male and two 

 female paratypes July 25, 1936, in rotten log mold at Drayton 15; holotype, 

 allotype, seven male, and two female paratypes sifting floor mold at Zetek 23 

 on July 27, 1936, and three male and four female paratypes same place and 

 date in log mold. 



The record with the termite is probably accidental. 



It should be noted that the sex ratio is nearly 1/1 and that the August 15 

 specimen and five taken in floor debris had just pupated. 



This isolated form is named for my friend. Dr. Charles H. Seevers. The 

 genus is nearest Dalmodes and Bythinophysis in Raffray's 1908 arrangement, 

 but is obviously distant from these genera on the absence of a longitudinal sulcus 

 on elytral flank, and an entirely different pronotum among other basic features. 



PHYBYTHARSIS new genm 

 This new genus is distinct from other Tychini on the following combination 

 of characters: (1) Head with vertex, front and clypeus highly modified in the 



