517 



Thorax. Pronotum trapeziform ; the 1st J or f rds with a strong, 

 transverse callosity, which does not extend to the sides, and poste- 

 riorly is often bounded by a furrow, the surface with 1 or 3 foveate 

 depressions; sides deflected or flattened in the middle; posterior 

 margin, across the scutellum, concave. Scutellum large, triangular ; 

 in the middle a slight, transverse incision, before which is mostly 

 a large depression. Elytra oval, convex ; Corium ; anterior margin 

 recurved or flattened on the basal , sometimes on the whole length ; 

 posterior margin straight as far as the 4th nerve of the membrane, 

 thence divergent to the point of the clavus ; membrane-suture 

 strong ; Membrane broad, rounded posteriorly, from the inner basal 

 angle, extending up the inner margin of the corium, at the outer 

 basal angle and the anterior margin coriaceous ; nerves, 5, not 

 extending to any of the margins, but roundly connected at their 

 ends, leaving a clear space all round them. Sternum : Prosternum ; 

 xyphus triangular ; Mesosternum short, in the region of the coxa? 

 with 2 deep depressions, middle furcate ; xyphus very short ; Meta- 

 sternmi short angled, depressed ; in the middle with a sub-rhomboidal 

 convexity. Legs of like form, 3rd pair longest ; thighs flattened ; 

 tarsi long, longest on the 3rd pair; 1st joint very short; 2nd 

 scarcely longer than the 3rd ; claws long, curved. 



Abdomen. Connexivum deep, reflexed. Genital segments; in the 

 $ 2, the 1st formed like the abdominal segments, but shorter and 

 narrower ; the 2nd much longer, visible above and beneath ; above, it 

 forms, in the middle, a keeled plate, at the end with curved horny 

 process on each side ; beneath convex, narrowed to the rounded 

 apex, and prolonged into 2 short processes. In the $ above (when 

 the elytra and wings are removed) all 3 segments are visible, the 

 ends of the plates of the 1st segment reaching to the end of the 3rd 

 segment ; beneath (under the prolonged 6th abdominal segment) are 

 the 2nd and 3rd segments, each in the middle with a somewhat broad 

 and long cleft, filled up by the 2 narrow, prolonged plates of the 1st 

 segment, which at the base enclose the ovipositor. 



All the species live on the margins of ponds and rivers, or on the 

 sea-coast, running, jumping, and flying with great activity, and very 

 difficult to catch. 



