310 PROCEEDINGS OF THE NATIONAL MUSEUM vol. m 



measurements. This matter is discussed in some detail in my previous 

 paper (1960) on Cherokia. The range of variation in the W/L ratio 

 in small series runs about 2% at the most. Part of this is due to 

 measurement errors, part to normal variability in the species. To 

 illustrate the specific differences, I give here a list of the four species 

 described herein, with the average W/L ratio for males in terms of 

 percentages: 



Boraria stricta 17.5 Boraria deturkiana 19.4 



Boraria media 20.4 Gyalostethus monticolens 22.1 



Sterna. — The metazonal sternal areas, unless produced into con- 

 spicuous subcoxal spines, have been generally disregarded by previous 

 workers on the Xystodesmidae, yet during the past few years I have 

 come to consider the sterna of paramount importance in the classifi- 

 cation of this family. In a previous paper (1958) I proposed the 

 anatomical term podosternum to describe the form occurring in the 

 genus Pachydesmus, and I can now outline a rough classification of 

 easily distinguishable variations. Generally speaking, the sternal 

 areas are much the same in both sexes, except for being proportion- 

 ately wider in females, and tend to be much the same in most or all 

 members of a given genus. We can consider, therefore, the sterna 

 to be usually generic in value as regards their systematic utility. 



(a) Unmodified: In essentially unmodified sterna, the coxae are 

 attached to sHght subcoxal elevations, there is no tendency for the 

 development of subcoxal spines, and usually such sterna are glabrous. 

 Normally the central area of each sterniun is about the same eleva- 

 tion as the adjoining part of the prozonite, and the interzonal furrow 

 or suture is thus not immediately followed by a raised surface. The 

 caudal edge of the metasternum is preceded by a flat margin, which 

 usually becomes wider at the midventral area. This type of sternum 

 occurs in Boraria, Dixioria, and some other genera. 



(b) Bilobed: In this category, the sternal siu-face slopes upward 

 from the interzonal suture, often is interrupted partially by a trans- 

 verse groove originating between the two pairs of legs, and culminates 

 in two broad obtuse lobes located between the coxae of the posterior 

 pair. Usually there is a short transverse row of setae between the 

 anterior legs, and an irregular field of setae on the lobes. In extreme 

 forms of this type, the posterior lobes may become produced into 

 acute subcoxal spines, and the sternal surface between them forms a 

 thin transverse edge that may overhang the true ventral edge of the 

 segment. Genera with this kind of sternum include Cherokia, Rhyso- 

 desrnus, Cleptoria, Dynoria, and Sigmoria. 



(c) Spined: In spined sterna, the surface is not elevated above 



