118 Bulletin Wisconsin Natural History Society. [Vol. 9, No. 3. 



Tetragoneuria semiaquea Burmeister 



This species, hitherto known as complanata Rambur and as 

 representing the extreme of the cynosiira-scmiaqnea-complanata 

 series, I regard as distinct. It is essentially an Atlantic coast 

 species covering the region from Massachusetts to Georgia. 



Its main distinction from cynosura and simulans is the smaller 

 size and the wing markings, though some minor points exist such 

 as the largely brown pile of the thorax — grayish-white in 

 cynosura — and the more marked tubercle on the superior appendix 

 of the male. 



Head, thorax and abdomen of typical coloration. T-spot 

 absent, never more than the stem visible in black. Thorax with 

 pile largely brown, so that it is little apparent. The lateral stripes 

 occasionally with a metallic glint. 



Wings with brown reaching to nodus. Three forms are 

 usual : 



i — color to nodus, often reaching- beyond nodus in the space 

 between M3 and Rs and M3-4, then to hind margin beyond level of 

 triangle, occasionally to hind margin at level of nodus. 



i2 — color to nodus, then in oblique irregular line to the anal 

 angle, or two to three cells along the hind margin, usually before 

 level of triangle. (Semiaquea type and complanata types). 



i3 — color to nodus, then in a nearly straight oblique line past the 

 triangle to the anal margin, usually leaving the lower end of the 

 anal triangle free. 



Extreme cases of simulans can be easily distinguished by the 

 transparent axial streak at the base of the wings which occupies 

 the median space, at least the centers of the cubital and hyper- 

 triangular spaces and part of the anal triangle, and finally the 

 arcular space, extending to near the level of the apex of the tri- 

 angle. In semiaquea these spaces are much infumated and the 

 hypertriangular and cubital spaces are brown, rarely with more 

 than lighted centers. 



The identity of this species occasioned the most puzzling 

 moments of the present study. The forms of these species seem 

 to be but a continuation of the forms f and g of simulans; so 

 I had originally supposed. Leaving the semiaquea series — that is 

 those specimens in which the color reaches the nodus — aside for 



