March, 1921] Macro-Fauna of Mirror Lake 161 



Family McsoveliidcE. 

 Mesovelia mulsanti White. This was abundant in Mirror 

 Lake, and second to one of the small Gerrids (see below) the 

 most abundant of all Heteroptera. It was commonest where 

 algae and duckweed were thick, and chiefly in the latter part of 

 summer. Most of the specimens were taken in September. 



Family Hebridce. 



This family is represented in local fauna by two species of 

 Merragata described by Drake ('17). 



Merragata brunnea Drake, was the only species found at 

 Mirror Lake. Apparently it was rare; only one brachypterous 

 specimen was taken, in among vegetation on the surface close to 

 shore at station 15. None were secured from the small pond 

 where it might have found favorable situations. 



Family Veliidce. 



Microvelia borealis Bueno. This tiny water strider was 

 common; possibly it should be listed as abundant. At least it 

 was abundant at station 17, September 13, when most of them 

 were found. The little pool was teeming with them, and many 

 more could have been secured than were. While only a few 

 were obtained at other stations, these were fairly well scat- 

 tered, so that it is quite likely that there were times when 

 they were numerous at more than the one locality. 



Drake found ('16) Microvelia americana (Uhl.), which he 

 said was more common than M. borealis Bueno. He also found 

 a new species, Microvelia hiuei Drake, recently described 

 (Drake '20). 



Family GerridcE. 



Gerris remiges Say. Somewhat surprising is the rarity of 

 this water strider, which has been called (Bueno '11) "perhaps 

 the most common of our species." Only one was found. Its 

 large size would prevent its being overlooked. 



Gerris marginatus Say. This was the most abundant 

 species of the family next to Trepobates pictiis and was undoubt- 

 edly a close third in general abundance among all Heteroptera. 

 It was taken throughout the collecting period in both adult 

 and nymphal stages. The vast majority were in the small pond 

 and none on the open water of the large pond; those from the 

 large were near shore where vegetation existed. This habitat 



