THE WATER-BOATMEN. 1073 



1220 (1446). Arctocorixa planifrons (Kirby), 1857, 284. 



"Head yellow; under surface black with two pale spots each side of 

 breast; occiput obtuse-angulate at middle, front blunt; prothorax cari- 

 nated, brownish-black, transversely streaked with pale yellow; hemelytra 

 brownish-black, sprinkled with yellow; anal half of abdomen pale yellow. 

 Length, 4 lines (8 mm.)." (Kirby). 



Described from Canada ; not recorded elsewhere. 

 Group II. — Arctocorixa. 



This group comprises a large number of species from the 

 eastern states which range in length from 3 to 8 mm. No key 

 to these smaller eastern forms has been published except a 

 partial one by Abbott (1913, 87) to the species known from 

 Georgia and a brief one covering six species in the Hemiptera 

 of Connecticut. These are based largely upon the number of 

 palar pegs present, and are of little value. The following key 

 is for a part of the species only. Brief descriptions of those 

 not in the key which have apparently been rightfully recorded 

 or are definitely known from our territory are therefore given 

 in alphabetical order, 1 "" as listed by Van Duzee in his Catalogue. 

 A number of these are doubtless synonyms, but from lack of 

 specimens I cannot determine which. 



PARTIAL KEY TO EASTERN SPECIES OF GROUP II. ARCTOCORIXA. 



a. Elytra with disks of clavus, corium and membrane dark brown or 



black, without lineations, their narrow margins yellow; length, 



6 — 6.5 m. 1221. hydatotrephes. 



aa. Elyti-a with more or less evident cross lineations of pale and dark. 



h. Dark pronotal cross-lines fewer than seven in number; length less 



than 5 mm. 



c. Dark cross-bars of pronotum distinctly wider than the pale ones. 



d. Larger, length 4.7 mm. 1222. seriata. 



dd. Smaller, length 3 — 3.5 mm. 1223. bradleyi. 



cc. Dark and pale cross-lines of pronotum of equal width; length, 



3 — 3.2 mm. 1224. abjecta. 



hh. Dark pronotal cross-lines seven or more in number. 



e. Inner basal third of clavus with a large oblique pale space devoid 

 of black markings; dark cross-lines of pronotum 10 — 12; length, 

 7.7 — 8 mm. 1225. EDULIS. 



1 "' 1 In addition to the smaller species of Arctocorixa below described, the follow- 

 ing have been mentioned or recorded from eastern North America, but they are 

 not included for the reasons given: A. abdominalis (Say), a Mexican species, recorded 

 by Banks from Florida, but no citation or other record: A. expleta (l'hl.1. a Colorado 

 species recorded from New Jersey by Smith (1910). probably on a wrong identifi- 

 cation: A. kirbi/i ( Fieb. ) = ( A. carinata Kirby). recorded from "Canada," but men- 

 tioned by Kirkaldy and Bueno (1909) as "doubtfully American": A. stigmata (Fieb.). 

 recorded from "North America." also mentioned by the same authors as "doubtfully 

 American": A. tarsalis and A. zimmermannii, both described by Fieber only from fe- 

 males, the former from Pennsylvania, the latter from Pennsylvania and "Carolina." 

 and neither since recognized. 



