1062 FAMILY XL. — CORIXID^E. 



Family XL. CORIXID^ 1 " Leach, 1815, 124. 

 The Water-boatmen. 



Oblong or oblong-oval aquatic Heteroptera of medium or 

 small size, having the body subdepressed above, more so be- 

 neath ; head short, wide, its front vertical, usually bluntly 

 rounded ; eyes very large, oval, feebly convex, coarsely granu- 

 lated, overlapping the front margin of pronotum ; ocelli want- 

 ing; beak short, scarcely differentiated from the face, the 

 mouth opening being on its front end ; antennae 4-jointed, in 

 repose concealed beneath the head, joint 3 longest, 4 setaceous ; 

 pronotum transverse, subpentagonal, its hind margin obtusely 

 triangular, in our species covering the scutellum ; elytra cori- 

 aceous, entire, covering the abdomen, often thinly pubescent, 

 the usual divisions usually distinct ; clavus large, its commis- 

 sure very long; membrane of same texture as corium, without 

 veins ; front legs short, their tarsi stout, 1-jointed, flattened 

 and usually fimbriate beneath ; middle legs longest, very slen- 

 der, their tarsi ending in two long, very slender claws ; hind 

 tibiae and tarsi compressed, fringed with long hairs, the tarsi 2- 

 jointed, claws wanting. 



The males differ widely from the females in having the last 

 three ventral segments distorted or asymmetrical (fig. 215, /) , 

 twisted (as viewed from beneath) either to the right (dextral) 

 or left (sinistral). They also have apparently two sets of 

 stridulating organs, one on one side of the dorsum called the 

 "strigil" (pi. XII, fig. 1) and composed "of rows of very closely 

 packed intensely black comb-like plates." The other is on the 

 front tarsi (or "palae") which are provided with one or two 

 rows of chitinous "pegs" or teeth. By rubbing these back 

 and forth over a roughened area on the femur of the other 

 fore leg, a twittering sound or mating call is produced. The 

 females lack these pegs and their ventral segments are per- 

 fectly regular (fig. 215, g) . The front legs are used mainly for 

 prehending food (fig. 215, /;), the long slender middle ones for 



""My treatment of this family is not such as I would wish. As stated on 

 page 6 of this work, I was unable to borrow examples of a number of the species not 

 in my collection, as the great majority of those from the various private cabinets of 

 this country (some of my own included) are, and have been for several years, in 

 the hands of the professed leading authority on the group. He not only ignored my 

 several requests for a loan of such species as I do not possess, but wrote that : "I 

 realize that the treatment of the Corixida? in your forthcoming work will be a 

 practically valueless contribution." In order to make it the more worthy in his eyes 

 I asked him to prepare the chapter on our eastern species, stating that I would 

 publish it under his name. This offer he also ignored. My work on the family is, 

 therefore, included as the best that I could do with the facilities at my command. 



