XIX. OXYBELUS. 105 
or black), the remainder black, with a transverse lacteous line 
on each side of the second towards the margin (sometimes, but 
rarely, a minute lacteous spot on each side of the third seg- 
ment), and the margin of the third, fourth, fifth, and apex of the 
anal segment, fuscous 9. 
The g differs in the face having a dense silvery pubes- 
cence; the antennz with the last joint bi-emarginate beneath, 
and having sometimes a lacteous mark within and beneath the 
first joint, and one (but rarely) on each side of the first segment 
of the abdomen, as weil as a minute one on each side of the third 
segment, which latter, as well as the mark beneath the first joint 
of the antenne, is generally deficient. 
g ¢ in my own and other Cabinets. 
+++ I captured this species in abundance at Hampstead, 
in 1833, but neither last year nor this (1835) could I find it 
in the same locality ; but I took a solitary specimen, in May 
last, at Highgate. It has also occurred in several other parts 
ofthe country. All practical Entomologists are well acquaint- 
ed with the curious fact of the periodical abundance of 
certain insects, which are then scarcely seen again for some 
time. This circumstance is fully confirmed by many insects 
of this tribe, which in some years are found in profusion, 
but which are exceedingly transient in their duration. It 
was in company with Arpactus tumidus that I found the 
above; they were also equally abundant and have likewise 
since disappeared; but 1833 was a year very rich in these 
insects generally. 
Genus XIX. Oxysetus. Latr. 
Heap transverse, subglobose, depressed in front, of the width 
of the thorax ; eyes oval, slightly prominent ; stemmata placed 
in an obtuse angle upon the vertex, the posterior pair on a line 
with the hinder margin of the eyes; the face covered with a 
silvery pubescence ; antenne short, arcuate, filiform, or very 
