266 PROCEEDINGS OF THE ACADEMY OF [PaRT II 



After careful study of the series at hand, the material previously 

 recorded as /. vilis Saussure from Paraguay and the Argentine, and 

 the literature, we are convinced that a single variable species is 

 represented. In coloration, a series of males from Sapucay, Para- 

 guay, agree with the male type of vilis, desribed from Corrientes, 

 Argentina, in having the lateral portions of the pronotum slightly 

 paler and more reddish than the dark brown remaining portions. 

 Three Paraguayan males, however, are at hand with pronotum 

 solidly colored. In the Argentinian material all of the males have 

 the pronotum solidly colored, varying from dark brown to rather 

 light reddish brown. In all specimens showing the bicolored prono- 

 tal condition before us, the femora are very dark brown the remain- 

 ing portions very contrastingly colored ; this limb coloration appears 

 in the Argentinian material, but shows slightly less decided con- 

 trast, varying to a condition in which the limbs are uniform light 

 brown. This latter condition is shown by the majority of the Ar- 

 gentinian males, as well as by two of the three Paraguayan males 

 with unicolorous pronotum. The vertex is individually dark or 

 pale. 



In the concealed genitalia we find the paired plate beneath the 

 supra-anal plate to be very large, the dextral plate much the larger, 

 with periphery rounded, bearing along its ventral margin numerous 

 spiniform hairs and near the distal portion of this margin with a 

 small, irregular, chitinous area, flanked byachitinous spine directed 

 distad. In the entire Paraguayan series this spine, though variable 

 in heaviness and length, is free and averages heavier than in the 

 Argentinian material showing that condition. In other Argentinian 

 specimens the spine is indicated only as a sharp, slender, chitinous 

 projection along the external margin of thesubchitinous area, which 

 is not free. It would appear to be true that the Paraguayan ma- 

 terial shows incipient racial differentiation, but this has not, in our 

 opinion, yet reached either sufficient degree or stability to war- 

 rant nominal recognition. 



Comparison of the females before us, with Giglio-Tos' description 

 of Lohoptera borelUi, shows that name to be based on material re- 

 presenting that sex of the present species. 



Measurements {in millimeters) . 



Length of Length of Width of Length of Width of 



cf body pronotum pronotum tegmen tegmen 



Sapucay, Paraguay (10) 16-17 4-4.2 5.. 5-5. 9 16.7-17.3 5-5.5 



Carcarana, Argentina (9) 12-15 3.2-3.8 4.4-5 14-16.7 4.1-5.3 



9 



Tucuman, Argentina (3) 17-17.2 5-5.3 7.3-7 5-5.1 3 . 3-3.4 



Carcarana, Argentina (4) 14-15.6 4.3-4.5 5.9-6.2 3.6-4.7 2.8-3 



Cordoba, Argentina 14.3 4.3 6 3.9 2.9 



