i8 University of Michigan 



effort, and for regulating the interchange of gases between the 

 bubble which they carry with them and the supply dissolved 

 in the water. This promises to be a very interesting problem 

 for future investigation. 



Key to tlie Species of Buenoa of the Douglas Lake Region 



Eyes strongly projecting laterally beyond the pronotum; head 



with eyes wider tlian body at its widest point; form more 



slender; meml)rane without a black transverse spot at base 



B. platycnemis 



Kyes not strongly projecting; head with eyes much narrower than 

 widest part of body ; form more robust ; membrane most 

 commonly witli a large black transverse spot outside near 

 base B. elcgar.s 



17. Buenoa platycenemis (Fieber). Found in the same 

 localities as B. cleyans, but mitch less common, less than a 

 dozen specimens being secured in 1918. My determination of 

 this species has not been veritied, as through an oversight no 

 specimens were sent to Air. Torre- JJueno. 



18. Buenoa cleyans (Fieber). Abundant in the peat bogs, 

 and also found occasionally in the larger beach pool at Sedge 

 Point. The adults were found only in the open water, and 

 v/ere commonly seen swimming at some little distance below 

 the surface ; but on several occasions nymphs of a lUienoa 

 were found among the emergent vegetation in shallow water 

 at Sedge Pool. 



A third species of Buenoa, B. niargaritacea Bueno, may 

 possibly occur in this region also. It was described from New 

 York, and has subsequently been reported from Florida, Illi- 

 nois, and Kansas, and I have seen specimens from California 

 and have found it very common in the vicinity of 

 Minneapolis and St. Paul, Minnesota. It may readily be 

 distinguished from either of the preceding species by its 

 shorter hemelytral commisure, which is distinctly shorter than 



