1878.] 437 [Uhler. 



Limnopouus Stal. 

 L. rufoscutellatus. . ; 



Gerris rufoscutellatus Latr., Gen., in, 134, No. 2; Stoll, Punaises, 

 tab. xv, fig. 108. Limnoporus rufoscutellatus Stal, Ofv., 1868, p. 396. 



No. 15, Harris' Collection. "Gerris marginatus Say, MSS., so 

 named by himself. Pond, Sept. 20, 1821." 



The specimen in the collection is a female of unusually small size. 

 After a close comparison of several individuals from various parts of 

 North America with specimens from Europe, I can find no permanent 

 differences to separate them. The species appears to be northern 

 and it has only twice been taken as far south as Maryland. 



Halobates Esch. 

 H. pictus. 



Halobates pictus H.-Schf., Wanz. Ins., vin, 111, figs. 882, 883. 



A single poor specimen now remains to represent this species. In 

 my own collection may be found specimens from Andover, Mass., 

 kindly collected for me by Mr. Francis G. Sanborn. 



This species is widely distributed, extending as far south as Cuba; 

 from which locality I have specimens sent to me by Prof. Felipe 

 Poey, of Havana. I once found a winged female near Baltimore. 

 It was swimming about in the midst of a large group of unwinged 

 specimens, and notwithstanding my repeated search, I have not since 

 met with another winged individual. Among the mountains of 

 North Carolina and Tennessee it is likewise unwinged, but commonly 

 more slender than is usual in the types from Maryland. 



Metrobates Uhlcr. 



Robust and broad. Winged form: head very convex, a little slant- 

 ing forwards, between the eyes narrower than long, much narrower 

 than the pronotum ; eyes very large, viewed from above placed ob- 

 liquely, subglobose, moderately prominent, their upper surface below 

 the line of the vertex, projecting widely over the sides of the prono- 

 tum; with one or two impressed lines running across near the middle. 

 Antennas stout, almost as long as the entire body, the basal joint 

 nearly as long as the three others conjoined, curved at base, and 

 narrowing in that direction, much stouter in the male, and a little 

 expanded at tip, the under side with erect hairs; second joint about 

 one-third the length of the basal one, greatly enlarged at tip ; the 

 third shortest, enlarged at tip; fourth very stout, fusiform, almost as 



