THE SMALLER WATER STRIDERS. 999 



which is not forked at tip as in the winged form of obesa, differs in hav- 

 ing the refiexed connexiva approximate, but not contiguous on apical 

 fourth of abdomen ; basal half of middle femora compressed, and first 

 dorsal genital more than twice as wide as second. Length, 3.6 — 3.8 mm. 



Marion and Putnam counties, Ind., Sept. 16 — 28 ; taken in the 

 former by scores from the base of clumps of water willow, 

 Dianthera americana L., growing in stagnant pools along the 

 margins of White River, five miles north of Indianapolis. 

 Nymphs were present in numbers and some of the adults mat- 

 ing. At hand also from New Lenox, 111., Aug. 8 (Gerhard). 

 Described from Brookings, S. Dak., and not recorded elsewhere. 



1137 (1312). Rhagovelia plumbea Uhler, 1894a, 217. 



Short, robust, subconical behind. Leaden gray or black with a bluish 

 tinge; a transverse median spot on pronotum, narrow edge of connex- 

 ivum, base of first antennal, trochanters, coxa? in part, and base of front 

 femora, yellow. Vertex much wider than in obesa, nearly twice the width 

 of eye. Antennae more slender, joints 2 and 3 united longer than 1, 3 

 slightly longer than 2, 4 one-half the length of 3. Beak reaching middle 

 of mesosternum. Pro- and mesonotum of wingless form as in obesa. 

 Abdomen wider, less compressed, its margins less elevated, the more re- 

 flexed ones of female widely separated. Middle femora distinctly longer 

 than hind ones, the latter but feebly swollen, those of males armed be- 

 neath at apical third with a pair of slender divergent curved setae-like 

 spines. Length, 2.5 — 3.2 mm. 



Chokoloskee, Fla., March 13. A colony of several hundred 

 was milling, mating and gyrating about among the row-boats 

 at the docks close by the village store. Recorded by Barber 

 from Indian River, Marco and Ten Thousand Islands, Fla. 

 Described from Grenada. Uhler (loc. cit.) says: "This is a 

 common species on the surface of salt water around the inlets 

 of the Florida Keys." Although he describes the hind femora 

 as unarmed, those of the males at hand are feebly spinose as 

 described above. The wingless form only is known. Champion 

 (1898, 140) says: "Wings would be of very little use to these 

 insects, the water upon which they live never drying up ; where- 

 as in the fresh-water forms, which have occasionally to migrate 

 in times of drouth, wings are a necessity, at least in a certain 

 number of individuals." 



III. Velia Latreille, 1804, 163. 



Oblong, rather robust, pubescent species having the front of 

 head subconical ; antennae longer and more slender than in the 

 other two genera; eyes coarsely granulated; beak reaching 



