212 MESSRS. T. BLACKBURN AND P. CAMERON ON THE 



pubescence, and therefore, I think, more shining and more 

 conspicuously punctured. This diiference, however, is so 

 strongly defined on the metathorax that I hesitate to 

 associate the two. 



21. Ody nevus vulcanus. 



O. vulcanus, sp. nov. ? . Robustus, vix nitidus, subtiliter 

 pubescens, fortiter punctatus, niger ; alis violaceis ; 

 clypeo vix emarginato ; abdominis segmento primo 

 fortiter transverso, antice vertical!, secundo fortiter 

 tuberculato-elevato ; metathorace rugoso. 



Long. 15-16 millim. 



This species is allied to the preceding, from which it 

 differs as follows : — The apex of the clypeus is scarcely 

 emarginate; there is no red spot on the forehead; the 

 punctures on the head are much deeper, and therefore 

 more distinct ; the system of larger punctures on the 

 prothorax, mesothorax, and scutellum is much closer and 

 deeper ; the metathorax is opaque and strongly rugose ; 

 the first segment of the hind body is very strongly and 

 rather closely punctate ; the second segment of the same 

 is a little less conspicuously elevated, and the wings are 

 violet rather than blue. 



Two specimens occurred at the same time and place as 

 the preceding. 



N.B. In my collection are two males and one female of 

 an Odynerus, taken on Mauna Kea, Hawaii, which I am 

 unable to separate from O. vulcanus, although they appear 

 somewhat more shining than a little rubbing would account 

 for. The length of these males is 13 millim. Their differ- 

 ences from the female do not seem to call for remark, 

 being only- the usual structural differences. The small 

 apical joint of iheir antennae is of a testaceous colour. 



