HEM1PTERA. l8j 



\Vater-boatmen, they can leap into the air from the water and take 

 flight. 



There are three genera in North Americ.i. The greater number 

 of our common species belong to Xotonccta. The following table of 

 the genera is from an unpublished work by Professor H. E. Sum- 

 mer 



Apices of hemelytra entire ; the three pairs of legs similar in shape. PLEA. 

 AA. Apices of hemelytra notched ; legs dissimilar. 



B. IK-iiu-iytra much longer than abdomen; fourth segment of antennae 



longer than third. AXISOPS. 



BB. Hemelytra but little longer than abdomen; fourth segment of antennae 



shorter than third. 



Family XIII. NEPID.E.* 

 ( Water-scorpions.} 



The members of this family can be distinguished from other 

 aquatic Heteroptera by the presence of a long respiratory tube at 

 the end of the abdomen. This tube con- 

 sists of two long filaments, each with a 

 groove on its niesal side. By applying 

 these filaments together the grooves form 

 ibe, which conducts the air to t\v<> 

 spiracles situated at the caudal end of the 

 abdomen. By means of this apparatus 

 tlu ible to rest on the bot- 



tom of a shallow pond, or among rubbish 

 or plant> in water, and by projecting this 

 tube to the surface obtain what air tb 



With regard to the form of tin- body 



two iferent types exist in this fam- 



ily. In on< ted by the genus 



long-oval, flat and thin; 



in ted by the genus 



:,itra. the body is almost linear and FIO. isi.-*/r- /. 



: 158). 



scorpion rorOUS; and with them the 



is fitted for seizing prey. In these legs the coxae 



. a *cot; 



