ELATERIDAE. 179 



Tarsi laAiellate beneath on several joints. Dendrocharia. 



Tarsi not lamellate. 2. 



2. Posterior coxal plates narrower externally. 3. 

 Posterior coxal plates parallel or broader externally. 17. 



3. Marginal groove of thorax beneath (for anteniiie) well marked. 4. 

 Marginal groove absent. 8. 



4. Prosternal sutures strongly arcuate. Stethon. 

 Prosternal sutures straight. 5. 



5. Marginal groove of thorax straight, continuing directly on the head. 6. 

 Marginal groove more or less interrupted by the eyes. 7. 



6. Marginal groove broad. Deltometopus. 

 Marginal groove narrow. Dromaeoliis. 



7. Tarsi simple. (Claws simple.) Pheenocerus. 

 Tarsi with fourth joint emarginato-excavate. (Claws usually den- 

 tate.) Fornax. 



8. Lateral margin of thorax with two ridges, sometimes a trace of a 



third. 9. 



Jjateral margin of thorax single. 11. 



9. Prothorax with well-detined antennal grooves be}ieath. 10. 

 Prothorax without well-defined (and limiteil) grooves. 



Adelothyreus. 



10. Antennse with joints 2—3 united shorter than tlie fourtli. 



Entomophthalmus. 

 Antennre with joints 2-3 united much longer than the fourth. 



Microihagus. 



11. Mandibles stout, external face rugose and at base with a backward 



prolongation. 12. 



Mandibles slender, not prolonged backwards. 13. 



12. Last ventral segment rounded at tip. Hypoccelus. 

 Last ventral prolonged in a point. Nematodes. 



13. Epistoma deeply sinuate each side. Schizophilus. 

 Epistoma regularly arcuate. 14. 



14. Coxal plates suddenly narrowed from the inner third. 16. 

 Coxal plates gradually narrowed. 15. 



If). Outer joints of antennae short(>r than the preceding. Cryptostoma. 



Outer three joints suddenly longer. Phlegon. 



16. Prosternal sutures arcuate. Anelastes. 

 Prosternal sutures straight. Epiphanis. 



17. Antennse slender, filiform. 



Tliird joint of antennre not longer than second. Xylobius. 



Third joint mucli longer than second. Hylochares. 



Antenna) dentate J withiu or bi-pectiuate ^. Sarpedon. 



