hungerford: aquatic hemiptera. 197 



of the male possess on the inner faces of the femora and tibiae peculiar 

 stridular areas. 



The tibial structure is borne on the inner face of a prominence, which 

 is formed by the elevation of the inner angle or margin of the tibia nar 

 its base into a thin but elongate spur. This spur is lacking in the 

 female, and not discovered in the nymphs. (See pi. XXIV, figs. 5 and 6.) 



The Development Changes. 



Head. The notocephalic margins of the eyes, which are near together 

 and nearly parallel in the adult, are relatively much farther apart in 

 the first instar nymph. In the newly hatched bug, the distance at syn- 

 thlipsis is nearly \z vddth of the head, with the margins of the eyes 

 diverging broadly to the vertex. As the development proceeds from in- 

 star to instar the eyes are brought nearer and nearer to their relations 

 in the adult where the synthlipsis is reduced to about 7.14 per cent of 

 the width of the head. 



The beak is 4-segmented and the antennse of the nymphs have much 

 the form of those in the adults. 



Legs. The general form as in the adult. The tarsi of all legs 1-seg- 

 mented and terminated by two claws. (The tarsi of the adults are 

 2-segmented and end in two claws.) 



Wings. The wing-pads are very conspicuous even in the later nymphal 

 instars. By the third instar the pads appear on the antero-ventral mar- 

 gins of the mesothorax as little flaps, the distal ends of which reach a 

 position on a line with the trochanter of the fore leg when flexed. In 

 the fourth instar they are much larger, the apices attaining to a 

 position on a line with the distal end of the mesothoracic tibiae when 

 the limb is flexed. In the fifth instar they are still closely applied to 

 the side of the thorax, but the tips of the more opaque pads reach a 

 point on a line with the distal ends of the hind coxae. 



Habits of the Species. Buenoa ynargaritacea is the common repre- 

 sentative of its genus in the ponds and pools of eastern Kansas. It ap- 

 pears to prefer the open water and is in much better equilibrium in 

 its watery world than the Notovectie. 



Individuals of this species may be seen in large numbers swimming 

 slowly or even poising in mid-water some distance beneath the surface. 

 They abound in waters teeming with Entomostraca, upon which they 

 largely feed, the crib formed by the closure of the anterior two spiny 

 pairs of legs being nicely adapted to the retention of such prey. Their 

 dexterity in the manipulation of this device and its efficiency in retaining 

 small beings may be demonstrated quite readily under the binocular, 

 and affords another of nature's illustrations of the fitness of form to 

 function. 



Like others of the predatory class of water bugs, they do, on occasion, 

 fall upon Corixids and other forms than the Entomostraca, but not with 

 the regularity of many of the others. 



Adults appear from early spring to late fall. The eggs may be found 

 in May, the nymphs begin to emerge by the middle of the month, and 



