198 THE UNIVERSITY SCIENCE BULLETIN. 
by the 15th of June form a dominant species to be noted in all stages 
of development, from egg to adult, in waters suitable to their needs. 
They are wilder and more difficult creatures to rear than the Noto- 
nectz, but no less interesting objects of study. So far as the writer is 
aware, there has been nothing noted hitherto concerning their biology, 
and he is glad to record for them something of the economy of their 
lives. 
Summary. This species is the common representative of its genus 
in Kansas ponds, where it swims well out from the shore and some dis- 
tance beneath the surface. It feeds on the small crustacean life of the 
pool which it gathers in a spiny crib formed by the closing of the four 
anterior limbs. Its eggs are placed in the tissues of submerged plants 
fixed or floating in open water. 
Family NAUCORID Fall 1814. 
Fallen, Spec. Nov. Disp. Meth., pp. 3, 15. 
A. TAXONOMY OF NAUCORIDA. 
Family characteristics. Broad, smooth bugs of moderate size, and 
greatly enlarged fore femora. The outer margin of the eye is continuous 
with the margin of the head, not protuberant, and caudal appendages 
are lacking. The antenne are shorter than the head and lie concealed. 
Ocelli are absent. The beak is 3-segmented. Membrane of the hemely- 
tra is without veins. The fore tarsi are 1-segmented; the middle and 
hind tarsi 2-segmented. The hind legs are not flattened for swimming. 
Aquatic, but little modified for such a life. 
KEY TO GENERA. 
A. Front margin of prothorax deeply excavated for the reception of 
the head. Ambrysus. 
AA. Front margin of prothorax not deeply excavated for the reception 
of the head. Pelocorig. 
Genus AMBRYSUS Stal. 1862. 
These Naucorids have the head set deeply into the prothorax. The 
body is oval or sub-oval, and the head transverse, and truncate behind 
the eyes. Beak very short, lateral margins of pronotum entire, posterior 
angles, slightly retrorsely produced; gular and prosternal carine of equal 
height, continuous, middle of mesosternum longitudinally very obtusely 
elevated and subsulecate. Anterior femora very broad. Anterior tarsi 
single segmented. Claws lacking, tibiz closely oppressed. 
The following adapted from Montandon: 
KEY TO AMBRYSUS. 
A. Pronotum smooth, shining, without punctation on the disc, some- 
times some rare indentations, set at regular intervals on the side. 
B. Head very wide—as wide, including the eyes, as half the 
width of the rear of the pronotum. 
C. With blackish spots or clouds. A. pulchellus. 
CC. Without blackish spots or clouds. Head and pronotum 
entirely yellow, immaculate. 
A. pulchellus var. pallidulus. 
