Notes on Hatvaiian Wasps. 187 



76. (81) Mesothorax very dull. 



77. (78) Mesothorax distinctly and rather strongly punctured ; 



propodeum conspicuously rugose, even in the posterior 

 concavity 0. vulcanus, Blackb. 



78. (77) Mesothorax at the most finely and very feebly punctured ; 



propodeum at most a little roughened, or with some 

 very feebly impressed coarse punctures, malcing it 

 subrugose. 



79. (80) Second ventral segment with a small depression, only 



distinct for a short way behind the costte. 0. cyphotes, P. 



80. (79) Second ventral segment with a large, wide, deep depression, 



extending more than half-way from the costaj to apex of 

 the segment 0. melanocpiathiis, P. 



81. (76) Mesothorax more or less shining between the punctures, 



never dull. 



82. (83) Depression of second ventral segment wide. 0. konamis, P. 



83. (82) Depression of second ventral segment not very wide. 



0. hiloensis, P. 



84. (65) Second dorsal segment simple, only ordinarily convex in 



profile ; mesothorax not shining ; depression of second 

 ventral segment only moderately deep at base or some- 

 times very shallow. 



85. (8G) Minute interstitial punctures of mesothorax under a very 



strong lens present, but very feeble and not dense, in- 

 conspicuous owing to the microscopic surface sculpture ; 

 apex of clypeus very slightly emarginate or truncate. 



0. peles, P. 



86. (85) Minute interstitial punctures of mesothorax very dense ; 



apex of clypeus often rather strongly emarginate. 



87. (90) Depression of second ventral segment very feeble or entirely 



wanting, wings not very dark and with little or no blue 

 iridescence, 



88. (89) Depression of second ventral segment feeble but present. 



0. neioelli, sp. nov. 



89. (88) Depression of second ventral segment wanting, surface flat 



beyond costae, the basal part of the segment consequently 

 appearing tumid 0. cooki, P. 



90. (87) Depression of second ventral segment quite distinct, wings 



dark with blue or steely iridescence. 



91. (92) Front of head finely and very feebly punctured. 



0. sociabilis, P. 



92. (91) Front of head densely and distinctly punctured. 



0. scoriaceus, P. 



