Notes on Hawaiian Wasps. 135 



44. (47). Second ventival segment with a large depression, deep in 



front, and extending back to or behind the middle of the 

 part of the segment behind the costfe ; propodeum at the 

 most slightly punctured or roughened, the posterior 

 concavity didl but smooth, and without distinct sculpture ; 

 mandibles red. 



45. (46) Mesothorax extremely dull with the punctures extremely 



feeble or obsolete ; apex of clypeus not deeply impressed 

 behind the emargination. ... 0. erythrognatJms, P. 



46. (45) Mesothorax not strongly but distinctly punctured ; apex 



of clypeus deeply impressed behind the emargination. 



0. orhns, P. 



47. (44) Depression of second ventral segment sometimes wide and 



well-marked (but much less deep than that of the two 

 preceding species), in which case the propodeum is 

 rugose ; if the propodeum is smooth, the depression of 

 second ventral segment is somewhat small and narrow, 

 not reaching to the middle of the part of the segment 

 behind the costa^ ; in some species the depression is very 

 shallow, and hardly or not perceptible ; mandibles dark 

 in nearly all the species. 



48. (49) A median spot behind the antennse, and some thoracic 



markings as well as the hind margin of basal abdominal 

 segment red. (Probably all except the median frontal 

 spot sometimes wanting). ... 0. tnesospilns, sp. nov. 



49. (48) Head, thorax and abdomen not red-spotted. Sometimes a 



yellow or yellowish median frontal spot. 



50. (55) Second dorsal segment more or less strongly raised from the 



base, not simply convex. 



51. (52) Puncturation of mesothorax very fine and feeble, sometimes 



obliterated O. cyphotes, P. 



52. (51) Puncturation of mesothorax very distinct. 



53. (54) Mesothorax very dull between the ^junctures. 



0. vidcanus, Blackb. 



54. (53) Mesothorax more or less shining between the punctures. 



0. hiloensis, P., and konanus, P. 



55. (50) Second dorsal segment simply convex. 



56. (57) Second ventral segment with the depression shallow, but 



quite distinct ; (thorax extremely dull, appearing greyish 

 from dense, very short, erect grey hairs ; puncturation 

 very feeble or obsolete) 0.peles,P. 



57. (56) Second ventral segment with the depression excessively 



shallow, or obsolete ; mesothorax more or less distinctly 

 pvmctnred. 



