1911] 



Muttkowski, Studies in Tetragoneuria. 



1'23 



Leg's black, fore femora pale. 



Abdomen slender, segments 2 and 3 inflated, 3 constricted at 

 middle, 3 to 10 thence slightly spindle-shaped, though much less 

 noticeably than in cynosura.. Sides with yellow interrupted lines as 

 usual. 



Appendages much like cynosura, but lacking the lateral ridge. 



2 . — Similar to the male. Wings with color extending to the first 

 antenodal. Abdomen without constriction at 3. Appendages longer 

 than in cynosura- Vulvars with lobes gently curved and sub-parallel, 

 somewhat U-shaped — not broadly divaricate and V-shaped as in 

 cyonsura. 



Length abdomen (including appendages) 27-29 mm., hindwings 

 26 to 28 mm. 



Fig-ure 4. — T. williamsoni n. sp. 



Material studied : 



A5. $ Wister, Okla., June 3. 1907 ; coll. Williamson. 



A6. 2 Wister, Okla., June 4, 1907 ; coll. Williamson. 



A7. $ Same as A5. 



Holotype male (A5) and allotype female (A6) in coll. William- 

 son, paratype male (A7) in Milwaukee Museum. 



This species falls exceedingly close to cynosura. Yet the 

 differences in the length of the female appendages and the form 

 of the vulvars are such as to make this species fully distinct. 



