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Sides of olypeus keeled Tribe I. ACHILINI. 



Sides of ciypeus not keeled ; thorax with three keels 



Tribe II. TRCTPIDUCTIINI. 

 Last joint of the rostrum short or very short. 



Head sometimes not narrower than the thorax ; thorax not keeled or with one 



obsolete keel Tribe III. DERBINI. 



B Ocelli most frequently 3, the third ocellus on the apex of the frons and seldom 

 wanting; vein of clavus reaching to the apex, or united with the suture of 

 the clavus near the apex Tribe IV. CIXIINI. 



Tribe I. • ACHILINI. 



TABLE OF GENERA, 



Anterior tibia; about equal to the femora and trochanters united, or somewhat 

 shorter. 

 Posterior tibire with one spine or without spines. 



Head and thorax of equal breadth G. i. Plectoderes, iSpinola. 



Head narrower than the thorax. 



Vertex short, transverse, not or scarcely prominent before the eyes, or con- 

 fused wilh the frons ; posterior tibiie with one spine. 

 Vertex distinct, anterior margin obtusely rounded or angulated ; thorax 



twice as broad as the head G. 2. Achilus, Kirby. 



Vertex, before the eyes, distinctly produced. 



Eyes subrotund, beneath scarcely sinuate; wings with elongate areas be- 

 fore the apical areas ; frons narrowed upwards 



G. 3. Helicoptera, A. et S. 



Tribe n. TROPIDUCHINI. 



TABLE OF GENERA. 



^'ertex truncate at base ; thorax slightly and broadly roundedly sinuated at base. . 4. 

 Vertex emarginated at base ; thorax posteriorly angularly emarginated. 



Radial vein forked before the middle or near the base of the wings 3. 



Radial vein of wings simple or behind the middle of wings, or at least much 

 longer at the base than the forked interior ulnar vein. 

 Wings oval, convex, horny, sprinkled with dense, depressed granules, obsoletely 



veined G. i . Grynia, Stal. 



Wings membranous, distinctly veined. 



Head depressed ; frons subhorizontal : wings with a series of strongly 

 oblique transverse veins, extending straight posteriorly and outwardly 



to the apex of the clavus G. 2. Tambina, Still. 



Frons more or less reclining, never horizontal ; anterior tibite equal in length to the 



femora and trochanters united or somewhat shorter. 

 Lateral margins of ciypeus distinctly keeled ; veins of clavus united very much 



behind the middle 2. 



Lateral margins of ciypeus obtuse, sometimes slightly keeled at base ; wings ex- 

 tending much beyond apex of abdomen. 

 Wings with a double series of transverse veins toward apex, exterior ulnar vein 

 simple. 



