1920] Parshley — Hemiptera Collected in Western New England 143 



Gerridse. 



Gerris remigis Say. 



Gerris marginatus Say. New to the Vermont list. 

 Rheumatobates rileyi Bergroth. New to the Vermont list. On a 

 quiet pond. 



In his Douglas Lake paper {I. c.) Hussey gives some interesting 

 observations on color variation in this species, which have led me to 

 examine some hundreds of specimens in my collection, representing 

 localities as follows: Plummers Island, Md.; Cold Spring Harbor, 

 Long Island, N. Y.; White Plains, N. Y.; Northampton, Mass., 

 and Woodford, Vt. I find that in the east, just as in Michigan, 

 specimens from northern localities show a reduction in the extent 

 of yellow pigmentation, and a few of the Vermont examples agree 

 perfectly with Hussey's description of his Douglas Lake form. It 

 would serve no purpose to give varietal names in this case, since 

 almost every imaginable intergradation and permutation of spot- 

 ting exists. In consulting Bergroth's review* of the genus, the 

 student must bear this variation in mind, since the color charac- 

 ters given for rileyi and tenuipes will not always hold. For ex- 

 ample, in rileyi the median mesonotal yellow spot is frequently 

 narrower than the pronotal spot and may in fact be absent, while 

 the diverging brown stripes of the mesosternum, stated by Ber- 

 groth to be characteristic of tenuipes Meinert, may occur also in 

 rileyi, though abbreviated before the posterior margin of the ster- 

 nite. These species may be distinguished with certainty by means 

 of structural criteria much as given by Bergroth, as follows : 



Mesonotum about as long as broad; male with hooked hairs of 

 middle tibise confined to basal half, hind legs twisted 



rileyi Bergroth. 

 Mesonotum longer than broad ; male with hooked hairs of middle 

 tibise extending nearly to apex, hind legs straight 



tenuipes Meinert. 



Searsburg, Vermont, September 5, 1919. 

 Saldidse. 

 Pentacora ligata (Say) . 



Taken on bare boulders in a rapidly flowing stream. 



' Fam. Gerrids. Subfam. Halobatin®. Ohio Nat., Vol. 8, 1908, pp. 371-382. 



