THE TOAD BUGS, 1023 



along the moist muddy, mucky or sandy margins of streams, 

 lakes and ponds, where their harmonizing colors protect them 

 from their enemies and where they feed upon the young of 

 other animal forms which live with them a littoral life. Only 

 about 25 species of the family are known, mostly from tropical 

 America. Of these, six, representing two subfamilies and three 

 genera, occur in the eastern states. The principal literature 

 treating of them is by Say, 1832; Stal, 1876; Uhler, 1884; 

 Champion, 1901 ; Bueno, 1905e, 1923 ; Hungerford, 1920, 1923c, 

 and Blatchley, 1925. 



KEY TO EASTERN GENERA OF XERTHRID^. 



a. Front tarsi with two claws; elytra with clavus, corium and mem- 

 brane present; eyes large, prominent, subpedunculate. (Sub- 

 family Gelastocorinas). I. Gelastocoris, p. 1023. 

 aa. Front tarsi with a single claw; elytra wholly coriaceous, with di- 

 visions not differentiated, the membrane absent; eyes small, sessile, 

 not prominent. (Subfamily Nerthrina?). 

 b. Elytra not soldered together along the middle line, their suture 

 distinct and disk without lines of elevations; scutellum strongly 

 narrowed apically to form a tongue-like wedge between the bases 

 of elytra ; margins of abdomen coarsely crenate. 



II. Glossoaspis, p. 1026. 

 bb. Elytra soldered together along the median line, their suture in- 

 distinct and disk roughened with oblique lines of short acute 

 elevations; scutellum broadly triangular, its apex obtuse; margins 

 of abdomen entire. III. Nerthra, p. 1028. 



I. Gelastocoris Kirkaldy, 1897b, 258. 



In addition to the characters above given, the members of 

 this genus have the body thicker in front than behind, finely 

 and densely granulate above; front of head triangular and 

 vertical ; eyes with inner and lower sides concave, the inner con- 

 cavity filled by a lobe of the vertex; pronotum with sides 

 strongly sinuate, front angles expanded, concave beneath, 

 forming with the lower concavity of eye a pocket for the re- 

 ception of the antennae ; front and hind margins of pronotum 

 strongly sinuate, disk of both pronotum and scutellum with ob- 

 long ridges or blunt tubercles ; inner margins of elytra sinuate 

 or curved and strongly overlapping, the membrane ill-defined, 

 base of outer margin of corium widened and flattened ; ventral 

 segments strongly narrowed at middle. Genital plate of male 

 asymmetrical, curved to the right ; middle of sixth ventral of 

 female strongly convex. Four species are known from our 



