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- 

 nectae, 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 op Naucorid^. 

 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 antennse 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 ai'e 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. Amhrysus. 



AA. Front margin of prothorax not deeply excavated for the reception 

 of the head. Pelocoria. 



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 carinae of equal 

 height, continuous, middle of mesosternum longitudinally very obtusely 

 elevated and subsulcate. Anterior femora very broad. Anterior tarsi 

 single segmented. Claws lacking, tibiae 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. pulcJiellus. 



CC. Without blackish spots or clouds. Head and pronotum 

 entirely yellow, immaculate. 



A. pulchellus var. pallixtulus. 



