178 NEOTROPICAL PSELAPHIDAE 



median fovea nearer base, all three foveae distinct and subequal in size, with 

 the median deeper than laterals; base with a row of about twenty coarse 

 punctures just posterior to the median fovea. 



Elytra with obliquely prominent humeri; each elytron with the flank 

 simple, an entire sutural stria, and no dorsal stria; base of each elytron with 

 four distinct foveae, each about the size of the median pronotal fovea. Meta- 

 thoracic wings well developed, translucent, the membranous surface appearing 

 minutely granular in dry specimens; each wing fringed with long setae, the 

 setae being 0.047 mm. in length. 



Abdomen with five visible tergites and stemites medianly. Tergite one 

 nearly four times as long as second; third as long as second; fourth about 

 as long as third; fifth transversely, irregularly ovate and not visible from 

 above, with a prominent median longitudinal tubercle on the basal half of 

 length, and with the apical half of the tergite irregularly and medianly de- 

 pressed near the junction with apical margin of last stemite, its surface more 

 coarsely punctate. 



First stemite wholly invisible between the posterior coxae ; second stemite 

 (first visible medianly) long, longer than the remaining stemites united; sec- 

 ond, third, and fourth visible stemites very short, subequal ; fifth visible ster- 

 nite (true sixth) as long as the two preceding united, with its apical margin 

 medianly produced or emarginate. 



Metasternum with a very long, longitudinal carina on each side, arising 

 at the lateral margin of the mesothoracic coxal cavity and extending poster- 

 iorly half the distance to the apical margin of the metasternum. This metaster- 

 nal carina is a very conspicuous feature of the species. Legs simple, typical 

 of genus and of the female sex, with the second tarsomere of the anterior tarsi 

 not dilated and flattened and not bearing a setal brush beneath. The first tarso- 

 mere is minute, the second large, the third relatively large but not as long 

 as the second, and bearing a single tarsal claw. 



Described from two female specimens, cotypes, collected by the author at 

 light at night, on Barro Colorado Island, Gatun Lake, Panama Canal Zone. 

 One specimen collected the night of July 7, 1936 and one the night of July 

 17, 1936. 



This is a very distinct species. At first these females were thought to be 

 associated with the two males of Scalenarthrus undecimtympiis. This asso- 

 ciation in the field was found to be purely fortuitous when they were analyzed 

 as the conspicuous pubescence, radically different ocular carinae of the ventral 

 surface of the head, and presence of well developed basal pronotal foveae of 

 Xybaris funiculis preclude such a point of view. 



The genera clustering around Xybaris are both difficult to separate 

 and not fully appreciated zoogeographically. The carinae of the ventral surface 

 of the head offer excellent material for future study. Thus the lower face of 

 the head, the region bounded by the mandibular bases and mentum apically, 

 the posterior margin of the tempora, and laterally by the eyes is seen to be 

 roughly trapezoidal in outline. On the field are five carinae: a median, longi- 



