56 Bulletin of the Brooklyn Entomological Society Vol. XI 



2. Intermediate and hind tarsi second joint longest; hind femora scarcely 

 incrassate in both sexes, not spinose; lead gray in color (subgenus 

 Trochopns Carpenter) R. plumbea Uhler 



Rhagovelia obesa Uhler, 1871, Proc. Bost. Soc. Nat. Hist,, 

 XIV: 107. This species is found in the rapid parts of streams 

 throughout the Atlantic States. In such places, they congregate 

 in schools, swimming powerfully in zig-zags against the current, 

 or at times sheltered behind some out jutting rock, placidly 

 paddling in the eddies that swirl about it. The peculiar tarsal 

 plume in this species and its striking function are descrif)ed in 

 detail in the Canadian Entomologist.* This is a difficult form to 

 confine in an aquarium, as it immediately takes to diving and 

 finally perishes. Rhagovelia obesa is sometimes found winged 

 about New York, but so rarely that my fifteen years of collecting 

 have yielded only seven. It is perhaps the most widespread 

 species of the genus and it has been suspected that some of 

 Champion's Central American species may be but unrecognized 

 variants of it. Central America seems to be the metropolis of 

 the genus, as most of the known species are thence. It has been 

 recorded from all the Atlantic States except Florida and is known 

 from Canada. 



Rhagovelia (Trochopus) plumbea Uhler, 1894, Proc. Zool. 

 Soc. Lond., p. 217 = Trochopus marinus Carpenter, 1889, Ent. 

 Mo. Mag., XXXIV: 78, pi. 3. This species is a denizen of 

 estuaries, bays and other brackish or salt waters on our southern 

 coasts and about the Antilles. There is only one other with a 

 like habitat, Rh. salina Champ., which is found on the Central 

 American coast cays. Nothing further seems to be known of its 

 habits. Its leaden hue alone is enough to distinguish it from its 

 near relatives, 



Microvelia Westwood, 1834, Ann. Soc. Ent. Fr., Ill : 647. 

 Hydroessa Burmeister, 1835, Handbuch, II: 213. Veliomorpha 

 Carlini, 1895, Ann. Mus. Civ. Gen., XXXV: 120. ' This genus 

 contains not only the smallest of the waterstriders, but also of all 

 the water-dwellers among the Hemiptera. It is very likely the 

 most abundant as to numbers and species, and the most widely 



* 1907, on Rhagovelia obesa Uhler, Vol. XXXIX : 61-64. 



