ADEPHAGA. 6 



is the lining that covers the sole of these dilated tarsi, or the kind of foot-cushions 

 with which they are furnished. These are of three descriptions. 



1. A dense brush of stiff hairs. This is to be found in the Cicindelidans, the 

 Carabidans, and the Chlcsniadans ; insects so furnished may be denominated 

 Sarrothropoda. I have noticed no particular variations of this kind of foot- 

 cushion ; in the last mentioned tribe, however, the Chlceniadans, the brushes are 

 broader, the consequence of the greater dilatation of the joints, than in the other 

 Sarrothropodous Geadephaga. 



2. The next kind of foot-cushions are formed of little membranous vesicles or 

 cysts, which are arranged in various ways in different tribes. In some, as Helluo 

 costatus, the hand is furnished with a compound cushion, there being a brush on 

 each side, and in the middle a line formed of short transverse rows of vesicles ; in 

 Anthia the dilated side of the joint only has a line of vesicles included between 

 lateral brushes ; in Brachinus and many others is a double oblique series of vesicles 

 on each joint ; in Agonum these vesicles are imbricated lying one upon another ; 

 in some, as in Harpalus interpunctatus of this catalogue, these little organs are 

 arranged without order, and cover the whole joint. In this respect this species 

 differs from the other Harpali, in which the vesicles are arranged nearly as in 

 Brach'mus. The insects that have this kind of foot-cushion may from it be named 

 Cystopoda. 



3. The third description of foot-cushions is when they are formed of peduncu- 

 lated cups or suchers, as in several of the Hydradephaga, particularly Dytiscus, in 

 whose hands may be seen two larger umbilicated cups with an infinity of minute 

 ones, which I have elsewhere described. 6 These may be named Pyxidiopoda. 

 The great object of all these formations is to enable the male to fix himself firmly 

 in coitu, which is probably done by producing a vacuum, for which at least the 

 cysts and cups seem particularly fitted, 7 and they may be rendered useful in tracing 

 the affinities of the different groups of the Section, as will appear under another 

 head. 



Geadephaga. Numerous, and seemingly inextricable, difficulties stand in the 

 way of a perfectly natural arrangement of this vast group, which includes the 

 whole of the Terrestrial Predaceous Beetles, for the Systematic Entomologist feels 

 quite at a loss, when he asks himself by which path shall I next proceed ? Though 



6 Introd. to Ent. iii, 693. "• Ibid, 691. 



B 2 



