( >ribata 



I 1 



. Lam. deeply excavated anteriorly so as to 

 J end in 2 long free points of about equal 

 26 length — 24. 



I Lam. truncated anteriorly — 27. 



I Dors, of Ahd. with a row of hairs near 



24 ' margin; terrestrial — 25. 



I Dors, of Abd. hairless; aquatic. — L. 550 p 21. O. aquatica p. 18 



| Ptm. reticulate with a dentate ant. margin. 



25 J — L. 600 p 26. O. quadridentata : . . . p. 19 



' Ptm. not reticulate nor with dentate margin — 26. 



t Psstg. org. clavate; hairs round Dors, of 



Abd. about 12. — L. 580 p 25. O. quadricornuta .... p. 19 



26 ' Psstg. org., setiform, strongly curved toward 



median line; hairs round Dors, of Abd. 



I about 18. — L. 450 p 22. O. berlesei p. 18 



I Outer lat. edge of Lam. strongly and 



27 \ irregularly dentate. — L. 390 p . . . 20. O. americana p. 18 



I Outer lat. edge of Lam. plain. — L. 210 p. 27. O. teeta p. 20 



, Dors, of Abd. with transverse furrows. — 



| L. 420 p. 23. O. languida p. 18 



j Dors, of Ab. without transverse furrdws. — 



I L. 650 p. 24. O. ovalis . . . , p. 19 



| Ptm. projecting forward nearly to tip of Post. — 30. 



29 < Ptm. truncated anteriorly not projecting 



beyond ant. margin of Abd. — 34. 

 | Projection of Ptm. pointed anteriorly. — 



30 L. 520 p 35. O. intermedia p. 21 



I Projection of Ptm. rounded anteriorly — 31. 



| Abd. with 2 large chitinous points projecting 



31 : from centre of hind margin — L. 650 p 37. O. mucronata p. 22 



I Abd. without such points — 32. 



| Psstg. org. short clavate. — L. 600 p. . . 29. O. alata p. 20 



32 \ Psstg. org. with long slender recurved 



peduncle and fusiform head — 33. 

 | Dors, of Abd. with fine longitudinal winkles. 



33 | — L. 850 p 39. O. rugifrons p. 22 



I Dors, of Abd. plain. — L. 700 p .... 33. O. dorsalis p. 21 



^ J Dors, of Abd. hairless — 35. 



\ Dors, of Abd. bearing conspicuous hairs — 39. 



| Abd. and Cephth. plainly divided — 36. 

 35 I No demarcation between Abd. and Cephth. 



— L. 900 p 31. O. centro-amerieana . . p. 21 



(Lam. hair strongly serrated and nearly 

 twice as long as Cephth. Intlam. hair 

 sharply recurved. — L. 430 p . . . . 28. O. agilis p. 20 



I Lam. hair, simple, setiform; Intlam. hair 

 I not recurved — 37. 

 < Lam. much shorter than Post. — 38. 

 ] Lam. nearly as long as Post.; Psstg. org. 

 fusiform, horizontal, directed forward. 



I — L. 320 p 30. O. avenifera p. 20 



I Psstg. org. short, clavate. pointed anteriorly. 



^ J directed forward. — L. 350 p .... 32. O. cuspidata p. 21 



| Psstg. org. long, recurved, with slender 



I peduncle and fusiform head. — L. 600 p 36. O. lucasi p. 22 



