246 Prof. J. C. Schiódte on the Morphology 
sharply defined, highly raised edges, but no spout-groove ; 
the evaporating-surface forms a narrow ring round the open- 
ing and a small spot in front of this. In Corizus crasstcornis 
the opening, which is placed far inwards on the sternum, is 
exceedingly small and difficult to find, punctiform, without 
spout-groove or evaporating-surface; whilst our other species 
of Corizus have a large, wide opening between the coxæ, with- 
out spout-groove, the evaporating-surface forming a narrow 
sharply defined strip covering both sides of the suture between 
meta- and mesothorax, of which latter the edge is finely and 
margin of the opening is very little raised. In Nysius the 
opening forms a long slit, with highly raised margins and 
short rounded spots; the evaporating-surface occupies the 
entire side of the metasternum, excepting the borders. 1n 
Phygadicus and Lygeus the form of the opening is as in 
‘Nysius, but there is no evaporating-surface. The numerous 
species of Rhyparochromus vary but little amongst themselves : 
i Slightly curved, 
with tubiform projecting margins and very short spout. In 
Geocorts the opening is oblong, with highly raised margins, 
but the evaporating-surface is confined to an indistinctly 
