On Aquatic Carnivorous Coleoptera or Dytiscide. 249 
the Dytiscide: with five-jointed front feet are very interesting : in some of the 
Agabini the male front feet differ but little from those of the female, being always 
however something larger and more powerful owing to an increase in the bulk of 
the three basal joints, which moreover bear beneath a peculiar pubescence, having 
a sugary or glandular appearance owing to the extremities of the hairs being 
peculiarly formed. In the Colymbetini there is usually a superior development of 
the male front feet to what we find in the Agabini; the basal joints being more 
dilated and some at any rate of the hairs on their under surface furnished with hairs 
bearing paper-like expansions or cups, sometimes arranged in transverse series 
(Colymbetes), It is however in the Dytiscini, Hydaticides, and Cybistrini, that 
we find a truly wonderful development of the male tarsi; in these groups, the 
three basal joints are not only enormously dilated, but are also accurately co-adapted 
with one another, so as to form a large circular (or transversely elliptical in Cybister) 
disc or plate, the under surface of which bears larger or smaller stalked cups or 
palettes, and sometimes also fine pubescence, while the edges of the plate are 
regularly fringed with spines or densely placed fringing hairs. The highest 
development is found in Dytiscus, Acilius, Cybister and Megadytes, where 
there are present on the under surface both fine hairs and very highly developed 
palettes. These remarkably constructed feet are powerful organs of adhesion to 
smooth surfaces and I believe also are highly developed sensitive organs. 
The claws of the front feet vary much, they are usually little developed in the 
Hydroporides, and are very delicate in Hyphydrus ; in the Macro-Dytiscidz on the 
other hand the front claws are always large, and are frequently remarkably 
constructed in the males, especially in the tribe Colymbetides. 
Deformity of the dilated tarsi of the males seems to be of frequent occurrence, 
I have observed it in several species of such different genera as Deronectes, Agabus, 
and Dytiscus. 
The Mippue Lugs are usually similar to, or differ comparatively slightly from the 
front ones, but their coxze are generally shorter and less conical, and the peculiar 
developments in the male sex are much less extraordinary. The cox are usually 
deeply embedded in their cavities, and are then always nearly globose, and this is 
invariably the case when they are well separated from one another ; when however 
they are nearly contiguous they become more or less elongate and conical, and project 
from their cavities, as is especially the case in the Vatellini and Sternopriscus. The 
trochanters and femora are very similar to those of the front legs, but are not the 
seat of such great modifications in the male sex. The tibize too are usually similar to 
the front ones, but often are slightly more slender and elongate ; their outer edge 
is always set with long cilize, and the front face in the Macro-Dytiscidee is nearly 
always roughened by bearing longer or shorter spines, the apex is always furnished 
with two spurs placed near one another at the inner margin: the extremity of the 
tibia is truncate nearly at right angles to its axis, and the edges of the truncature 
