230 BULLETIN 182, UNITED STATES NATIONAL MUSEUM 



6. Neck less than one-fourth as wide as head XLVII. Ophites 



Neck more than one-fourth as wide as laead 7 



7. Elytra with a pleural fold near side margin XLV. Homoeotarsus 



Elytra without trace of a pleural fold 8 



8. Labrum not dentate XLVII. Biocrypta 



Labrum bidontate (the denticles sometimes obtusely rounded). 



XLVI. Ochthephilum 



9. Fourth segment of maxillary palpus net strongly compressed nor very short, 



glabrous 10 



Fourth segment of maxillary palpus compressed, truncate, and pubescent. 



XLIV. Paederus 



10. Neck never less than one-fourth as wide as head; apex of posterior tibia 



with a distinct clenidium on both sides 11 



Neck variable; apex of posterior tibia with a distinct ctenidium only on 

 inner edge " 13 



11. Fourth segment of maxillary palpus longer than greatest width of third; 



labrum semicircularly emarginate; punctation dense and umbilicate. 



XLI. Scopobium 



Fourth segment of maxillary palpus shorter than greatest width of third ; 



labrum bilobed or triangularly emarginate; punctation generally not \im- 



bilicate 12 



12. Elytra with a pleural fold near side margin XLIII. Lobrathium 



Elytra without trace of a pleural fold XLII. Lathrobium 



13. Neck (usually) one-fourth as wide as head, or more 14 



Neck one-fifth to one-eighth as wide as head 20 



14. Antennae with first two segments larger, rest verticillate, slender, of equal 



thickness throughout XXXI. Thinocharis 



Antennae normal 15 



15. Pronotum distinctly longer than wide ; seventh abdominal sternite in male 



generally distinctly modified ; punctures of head not distinctly umbilicate 



though not very fine XXXVII. Onis 



Pronotum not or scarcely longer than wide; seventh abdominal sternite of 

 male rarely modified ; punctures of head umbilicate or fine and dense- 16 



16. Head and pronotum den.sely and very finely punctate or sculptured, without 



any umbilicate punctures except at margins XXXII. Lithocharis 



Head with few or many distinct umbilicate punctures, surface sometimes 

 densely punctulate 17 



17. Labrum without median tooth 19 



Labrum with median tooth or prominence 18 



18. Umbilicate punctures of head sparse and not strong XXXIII. Aderocharis 



Head densely and strongly umbilicately punctured XXXIV. Stilomedon 



19. Gular sutures distinctly diverging po.^teriorly fi-om before middle. 



XXXV. Sunius 

 Gular sutures most approximate along middle or at base_ XXXVI. Medon 



20. Gular sutures always united, at least basally XL. Rugilus 



Gular sutures never united in any part (although often very closely approxi- 

 mated) 21 



21. Labrum not dentate, feebly emarginate; vertex sometimes carinate in males. 



XXXIX. Monista 

 Labrum not denticulate, truncate and narrowly emarginate. 



XXXVIIL Scopaeus 



^' Further oxaminntion shows that tliis character is rather misloadinp:. The presence of 

 threo or four spiniiles in a row wpH liehiw (lie apox is not snthcient to phice t)ie specimen 

 In this half of the couplet ; the row must be definite and extend almost to the apex. 



