On Aquatic Carmvorous Coleoptera or Dytiscide. 837 
and bearing each a fine seta which does not project beyond the margin, these sete are 
in some species more numerous and crowded together at the extremity and there 
collected into a kind of depression on the face of the femur, but do not project beyond 
its margin. The tarsus is a little longer than the tibia and is terminated by two 
equal claws, the basal joint is about as long as the three following ones together. 
The species of this genus as yet known are peculiar to the European and 
Mediterranean region with one in Japan. Noterus leevis is the highest, Dytiscus 
clavicornis the lowest species of the genus ; there isa very great difference between 
the development of the swimming legs in these two forms: the former species shows 
also the greatest development of the sexual characters, and is remarkable also for 
the accumulation of setze at the extremity of the hind femora ; in this latter respect 
N. japonicus is intermediate between it and the other species, 
The genus presents a very interesting peculiarity, consisting in the development 
of patches of dark colour, on the undersurface of the body and legs in the male sex 
only. 
I. 7.—Genus COLPIUS. (Vide p. 267.) 
This is an isolated insect, of subhemispherical form, but nevertheless acuminate 
behind ; the surface is dull, the upper face covered with a dense fine sculpture, the 
lower with an extremely coarse irregular sculpture. The antennze are rather 
slender and subserrate internally. 
The apical joint of the labial palpusis dilated and notched ; the prosternal process 
is large, and broad, not truncate behind, but only very obtusely acuminate, it is 
bordered by a raised margin, and is continued forwards quite on one plane, till at 
the anterior margin of the prosternum it presents a vertical face; the anterior 
transverse band of the prosternum is small, the rather large coxz being placed near 
the front margin. The middle coxz are small and globose ; the metasternum seems. 
to be separated from the hind coxa by a nearly straight transverse suture, which 
however is rendered extremely obscure by the coarse sculpture ; the coxal processes 
are very broad, and become broader behind, but their outer angles are very little 
produced backwards, the coxal cavities are separated by a rather broad space. The 
epipleuree of the elytra are very broad at their basal portion, and continue distinct, 
although narrow, till near the extremity of the body. The front legs are extremely 
modified, and most peculiar: the femora are subcylindric and a little curved; the 
tibize are articulated and shaped in such a manner that what should be the outer 
edge is the lower one, and the inner edge is the upper one, the natural front face look- 
ing outwards ; the upper edge is rounded and polished and terminates in an elongate, 
stout, acuminate hook, this appears to be continuous with the tibia and the tarsus 
has the appearance of being inserted at a distance from the extremity. The basal 
joint of the tarsus is about as long as all the other joints together, and 1s in the 
male much incrassate. The intermediate legs are feeble. The swimming legs are 
5P 2 
