80 Bulletin of the Brooklyn Entomological Society Vol. XV 



AN AMERICAN SPECIES OF CYMATIA (CORIXID^, 

 HEMIPTERA). 



By Roland F. Hussey, University of Minnesota, Minneapolis. 



While collecting waterbugs at a small pond near St. Paul, 

 Minnesota, in the fall of 1918, I observed numerous individuals 

 of a Corixid species which was notably distinct from all the 

 other species of the family with which it was associated. On 

 each of my visits to this pond I found this form to be one of the 

 most abundant waterbugs in the habitat; and in January, 1919, 

 I found large numbers of this species hibernating in groups of 

 from ten to fifty individuals in air-pockets in the ice which 

 covered the pond. This remarkable mode of hibernation is 

 being investigated, and will be discussed in a future paper. The 

 species was much less abundant, however, during the next fall 

 and winter : less than a dozen individuals were found between 

 October, 1919, and January, 1920. 



The pond from which these Corixids were taken is small, less 

 than 100 yards in diameter, and not very deep. The bottom is 

 soft and mucky, and there is very little aquatic vegetation, at 

 least in the parts where most of the collecting was done. 



I have also found this species among some Corixids from 

 North Dakota, which were sent to me recently from the Museum 

 of Zoology of the University of Michigan. These bugs were 

 taken quite fortuitously by Miss Crystal Thompson frorh among 

 the aquatic vegetation at Fort Totten Lake, while she was 

 making Birge-net collections of Crustacea under the direction 

 of Professor R. T. Young at the North Dakota Biological Sta- 

 tion. Through Mr. F. M. Gaige of the University of Michigan 

 Museum, Miss Thompson has kindly furnished me some data 

 concerning the habitat. 



Fort Totten Lake is a shallow, weedy body of water, less than 

 a quarter of a mile in diameter, located about a mile and a half 

 from Devil's Lake. It is the only body of fresh water within a 

 radius of five or six miles. The bottom is rather firm and sandy, 

 with considerable debris, and there is a rather plentiful growth 

 of Chara, Ceratophyllum, etc. The lake has neither inlet nor 

 outlet. 



