AQUATIC INSECTS IN NEW YORK STATE 357 



;^" 



28 " Body gray with a white milky luster, specially the pleura 



and pectus. Legs tawny, femora and tibiae with irregu- 

 lar piceous bands, tarsi piceous. Length 2.5mm. Hudson 

 Bay Ter." This is a synonym of vittatum Zett 



according to Mr Coquillett (1898j decorum 



Thorax fuscous or cinereous pollinose, humeri pallid, pleura 

 pale cinereous, scutellum pale at the tip; abdomen black- 

 ish; fore coxae pale, middle and hind ones cinereous; 

 femora pale at the base, black at tip; tibiae black. Length 

 3mm. Mexican species cinereum 



29 Abdomen somewhat shining, yellowish gray or whitish at 



the sides, and yellow at the base; legs brown, tibiae and 

 fore coxae white, tip of tibiae and all tarsi black. Euro- 

 pean species, also occurring in Greenland reptans 



Basal segments of abdomen opaque, distal four segments 

 somewhat shining black or brown. Two long hairs at the 



tip of the first and third fore tarsal joints (ZO) 



■30 Legs reddish yellow, tarsi black, except proximal half of 

 middle and hind metatarsi which are light yellow. Length 

 2mm. (St Vincent island) This is a synonym of 

 pulchrum Phil, according to Hunter t a r s a I e 



Legs black, base of tibiae, first joint of middle and hind 

 tarsi and sometimes base of femora yellow; extensor sur- 

 face of all the tibiae more or less whitish. A widely dis- 

 tributed and variable sjjecies venustum 



31 Length 1.5mm. Front and middle femora and tiliiae wholly 



yellow; hind ones, except apices, also yellow. (Colorado). g r i s e u m 



Length 2.5mm. Legs brownish black, distal part of femora, 

 base of tibia, and greater part of metatarsi light yellow. 

 (California) a r g u s 



Some of the characters used in this table have been taken 

 from the key given in United States Department of Agriculture, 

 division of entomology, bulletin 10, new series, 1808, page 68, 

 by Mr Coquillett. In the table given above, I have included all 

 the North American species. For the southwestern and Mex- 

 ican species it should however be used with caution as I did not 

 liaye specimens of some of these. 



Descriptions of the species 



S. argus Williston 



N. Am. Fauna, No. 7. May 1893. p.253. Cal. (Syn. of S. vlttatum 

 Zett. according to Coquillett, Harriman Exp. 19(X>. p.393) 



Female. Black, the legs in part light yellow; front black, 

 opaque; face cinereous, with whitish pubescence; antennae 

 brownish black, the basal joint yellowish; thorax black, the 



