THE CANADIAN ENTOMOLOGIST. 117 



NOTES ON CORIXID^: NO. i [HEM.]. 



BY G. W. KIRKALDV, HONOLULU, H. ISLANDS. 



Species of the Corixidn^ cannot be mistaken for those of any other 

 family of Hemiptera. The remarkable structure of the mouth-parts 

 (which caused Borner to elevate the family into a separate suborder, 

 Sandalioerhyncha), and, in the males, the possession of two sets 

 (apparently) of stridulating organs, abundantly separate them from any 

 other family. Although not so specially adapted, to our eyes, for such a 

 life, the Corixidae have gained a more complete mastery over the problems 

 of aquatic existence than their relatives, the Notonectidae and Naucoridae, 

 if we may judge by the much greater number of their species. 



The structure of the Corixidae is extremely interesting, and there are 

 probably no other insects whose males can boast of at least four separate 

 secondary sexual characters (of these, two are of great specific importance). 

 Their stridulation and general biology have recently been briefly summar- 

 ized by myself* 



The genera of Corixidse may be tabulated as follows : 



1. Scutellum covered by pronotum only at the anterior margin ... .(2) 

 I a. Scutellum covered (except sometimes at posterior angle) by 



pronotum (4) 



2. Metapleura simple. Minute species, never over 5 mill. long. . . .(3) 

 2a. Metapleura deeply impressed behind, forming so-called "parapleura" 



species over 6 mill, long 3, Dia_f>repocoris, Kirkaldy 



3. Pronotum truncate, or (generally) convex 



behind i, Micronecia, Kirkaldy 



3a. Pronotum roundly emarginate behind 2, Tenagobia^ Bergroth 



4. Males (5) 



4a. Females = (10) 



5. Strigil absent (6) 



5a. Strigil present (7) 



6. No stridular area; hind tarsi not marked with black . . 4, Cynnatia, Flor 

 6a. Stridular area present ; hind tarsi usually marked conspicuously with 



black (the segment itself, not the fringe of hairs 



only) 5, CaUicoj'ixa, White. 



*" The stridulating- orgfans of Water-bug-s, especially of Corixida?," 1901, J. 

 Quekett Micr. Club (2), viii, 33 46, Pis. 3-4 (often cited as " Quebec I"), and 

 "A Guide to the Study of British Water-bug-s," 1905, Entomologist, XXXVIII, 

 231-6, etc. 

 April, 190S 



