120 THE UNIVERSITY SCIENCE BULLETIN. 



First Ins tar. 



Size. Length of body, .676 mm.; width, .364 mm.; width of head, 

 .338 mm.; length of middle limb, 1.43 mm.; hind limb, 1.04 mm. 



Shape. Remarkably like that of Gerris. Head, thorax and abdomen 

 closely joined. The indentation between the prothorax and mesothorax 

 being more marked than that between the head and prothorax. The 

 sides of the body parallel and the abdomen extremely short. Tip scarcely 

 reaching distal end of posterior coxae. 



Color. Yellowish brown, a light Y-shaped line is present upon the 

 head, the stem of which passes posteriorly across the prothorax and 

 widens to a broader band covering the median line of the long meso- 

 thorax which is met posteriorly by converging lateral bands of the same 

 color. Eyes dark red, some pink spots show in the 1st, 2nd, and base 

 of the 4th segments of antennas. These are now almost obscured, but 

 doubtless gave the pink color spots to the embryo within the egg shell. 

 Limbs are smoky testaceous, but fairly light, as on the venter of the 

 bug. The tip of the beak and the suture lines in front of the mesocoxae 

 being dark. 



Genus RHEUMATOBATES Bergr. 



Rheumatobates rileyi. 



Habitat. There are three species of this peculiar group of little 

 bugs. They live on quiet waters. In Kansas R. rileyi is common enough 

 on the muddiest ponds and pools. The male of this species is of most 

 bizarre shape. (See plate XVI.) Note the clasping antennae and the 

 strange twist to the hind femora. 



Oviposition. Three summers have failed to disclose the nature of the 

 oviposition. The ovipositor suggests that the eggs are hidden in the 

 tissue of a plant. The writer figures this on plate XVI. 



Food Habits. They feed upon insects dropped upon the water, and 

 if watched in a pool teeming with ostracods they can be seen to scoop 

 them out of the water and carry them about on the upturned tip of the 

 beak. 



Behavior. These insects are gregarious and very easily disturbed. 



DESCRIPTION OF STAGES. 



The Ovum. 



Size. Length, .728 mm.; vddth, .208 mm. 



Shape. Elongate cylindrical; one end bluntly pointed; the other 

 end rounded and bearing a short projecting micropyle. 



Genus HALOBATES Eschs. 



Two species, H. micans, off the coast of Florida and H. sericeus off 

 the coast of California. Little is known about these insects. Eggs 

 found on a floating feather by the Vitor Pisani expedition appeared from 

 the embryo within to be eggs of Halobates. Other females taken have 

 been figured with eggs extruded and clinging to the abdomen. Their 

 food must be the minute Crustacea of the water, for they range far 

 from land and are taken on coast only when driven there by storms. 



