No. 34-] HEMIPTERA OF CONNECTICUT: VELIIDAE. 419 



may some day make a very fascinating study of its life history. 

 Its leaden hue alone is enough to distinguish it from its near 

 relatives, aside from the differences noted in the key, its long, 

 slim legs, its short body, and the other characters indicated by its 

 authors. 



Microvelia Westwood. 



Ann. Soc. Ent. Fr., iii, 647, 1834. Hydroessa Burmeister, Handbuch, ii, 

 213, 1835. Veliomorpha Carlini, Ann. Mus. Geneva, xxxv, 120, 1895. 



This genus contains not only the smallest of the water-striders, 

 but also of all the water-dwellers among the Hemiptera except 

 Helotrephes in the Notonectidae. It is probably the most abun- 

 dant as to numbers and species, and the most widely distributed, 

 since it is known from all the continents and nearly all the islands, 

 and occurs in every zoological region. Be it pond, lake or stream, 

 it is always possible to secure these tiny beings, hiding among the 

 grasses or walking about the banks or stalking their game on the 

 green fields of duck-weed floating on some placid pool. This 

 genus also is dimorphic and some of its species polymorphic, and 

 here again the winged and wingless forms are so notably different 

 that they have frequently been taken for distinct species. The 

 thoracic structures of the apterous forms also affords excellent 

 differentiating characters. However, in the antennae we have 

 such excellent characters that it is always possible to bring together 

 both forms of any one species and to differentiate them from 

 other species, even though closely related. This antennal character 

 is largely employed in the following key since it is easily applicable 

 to both the winged and wingless forms : 



Key to Species. 



1. Antennae longer than head and thorax taken together; posterior 



tibiae straight in both sexes 3 



Antennae equal to or shorter than head and thorax taken together 2 



2. Antennae shorter than head and thorax taken together; posterior 



tibiae curved in male; female orbiculate, male elongate borealis 



Antennae equal to head and thorax taken together; posterior 

 tibiae straight in both sexes ; sexes similar in form hinei 



3. First and third antennal joints subequal in length 4 



First antennal joint shorter than third, fourth subequal to second 



and third taken together. Hemelytra much marked with white; 

 apterous form glabrous, slender albonotata 



4. Fourth antennal joint much shorter than two and three taken 



together 5 



Fourth antennal joint slightly longer than second and third taken 

 together buenoi 



5. Apterous^ form with dorsal patches of silvery white pile; hem- 



elytra in winged form imicolorous; a moderately large, stout 



form americana 



Apterous form with dorsal patches of blue-gray pile ; winged form 

 unknown ; rather small, fusiform species fontinalis 



