152 
A single specimen of this most distinctive insect occurred 
in February on Mauna Loa, Hawaii, at an elevation of 
about 4,000 feet, near the crater Kilauea, flying in the 
forest. Another (much dilapidated) specimen taken 
at the same time and place, is probably conspecific, 
but if so has lost the beautiful colour from the wings. 
It is devoid of pubescence and, therefore, I think 
more shining and more conspicuously punctured. 
This diflerence, however, is so strongly deflned on the 
metathorax that I hesitate to associate the two. 
21. — Odynerus vulcanus. 
0. vulcanus, sp. nov. $ Rohustus ; vix nitidus ; suhtiliter 
puhescens ; fortiter punctatus ; niger, alls violaceis ; clypeo 
vix marginato ; abdominis segmento primo fortiter trans- 
verso antice verticali, secundo fortiter tuherculato-elevato ; 
metathorace rugoso. 
Long. 15 — 16 mm. 
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 there- 
fore 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 con- 
spicuously 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 0. vulcanus, although 
they appear somewhat more shining than a little 
