CORIXINA. 49 



the third. Eyes remote, slightly prominent. Eostrum 3-jolnted, 

 short, obtuse ; the first joint nearly covered by the labrum and cheek- 

 plates. Fronotum convex, transverse, obscurely hexagonal. Elytra 

 corneous ; Corium, the posterior margin of each elytron meeting each 

 other in a straight longitudinal line ; Emholiiim linear, placed ob- 

 liquely on the anterior angles ; Membrane wanting. Sternum visible 

 horizontally only as the edges of thin plates between the deeply 

 inserted coxa?, laterally as triangular plates. Ijeys all formed alike ; 

 coxo} large ; fulcra, third pair angulated ; thighs gradually smaller to 

 the apex ; tarsi trimerous. Gen. 1, Plea. 



Section q.— CORIXINA. 



Notonectici, p., Burm. 

 Notonectidse, p., Westw. 

 Corisides, Am., ef Serv. 

 Corisoidae, Ficb. 

 Corisidea, Fleb., Floi\ 

 Corisae, Ficb. 



Head scutellate, greatly curved under, so that the apex rests 

 between the anterior coxae, the posterior margin overlying the pro- 

 notum. Antennce^ simple, 3 or 4-jointed, inserted under the margins 

 of the head. Eyes large, remote. Eostrum short, unarticulated, 

 concealed ; labriim triangular, transversely wrinkled ; labium smooth, 

 covered by the labrum. Eronotum transverse triangular. Scutellum 

 0, or short, triangular. Elytra pergamentous throughout ; Embo- 

 Z/wOT long, linear ; Clavus broad, triangular ; Membrane indistinctly 

 separated from the corium ; nerveless except one fine, long inner 

 nerve. Wings ample, very delicate. Sternum with Scapulce, Eleurcs, 

 and sometimes Earapleurce ; Prosternum anteriorly bilobed ; Meta- 

 sternum produced into a triangular xyphus. Legs : each pair of dif- 

 ferent form ; first pair inserted posteriorly on the prosternum, stout, 

 short ; the tarsi monomerous, broad, cultrate, differing in the sexes, 

 pectinated, with strong hairs beneath, and one small setaceous, 

 apical claw; second pair, the thighs longest, simple, tarsi 1 or 

 2-jointed, with two long claws ; third pair, tarsi long, dilated, 

 2-jointed, long-ciliated, and with one apical claw. 



4 



