1032 FAMILY XXXVII. — NEPIDjE. 



debris on the bed of an extinct pond. The females are easily 

 separated from those of femoratus by the deeply cleft sixth 

 ventral, while the males are difficult to distinguish. Recorded 

 also from St. Augustine, Titusville and Lake City, Fla., and 

 known only from that State, North and South Carolina and 

 Kansas. At Lake Ellis, N. Car., the type locality, it "fairly 

 swarmed in the lake among the water-weeds." 



Family XXXVII. NEPID^E Latreille, 802, 252. 



The Water Scorpions. 



Aquatic insects of very diverse form but agreeing in having 

 the head porrect ; ocelli absent ; beak subulate, 3-jointed, very 

 short; antennae 3-jointed, in repose concealed in a pocket be- 

 neath each eye; elytra entire, usually covering the abdomen, 

 the clavus, corium and membrane distinct, the membrane with 

 reticulate veins; front legs raptorial, inserted very near the 

 front margin of prosternum, their coxae elongate, femora 

 grooved beneath for the reception of the tibiae and tarsi, the 

 latter 1-jointed ; middle and hind legs more slender, not flat- 

 tened, fitted for crawling, their tarsi also 1-jointed and ending 

 in a pair of long slender divergent claws ; abdomen furnished 

 behind with two long, slender bristles, these grooved on the 

 inner side, and when fitted together forming a respiratory tube. 



The members of this family inhabit, for the most part, shal- 

 low stagnant water and delight in the mud and decaying vege- 

 table matter which accumulates on its bottom. When they 

 wish to take in a supply of air they rest on their long legs or 

 cling to a submerged plant and project the end of the abdominal 

 tube above the surface of the water film. They have the power 

 of stridulation or making a noise either to attract their mates 

 or to express some emotion. Bueno (1903a, 235; 1905c, 85) has 

 described the stridulation of Ranatra fusca, which at times pro- 

 duces a "rasping creaky chirp." 



"This is produced by a 'tonal apparatus' situated in the deep and 

 elongated coxal cavities of the first pair of legs and consists essentially 

 of two opposing rasps, one on the coxa near the base and the other on 

 the inner surface of the front margin of the lateral plate of the coxal 

 cavity. The sound is made both in and out of water by the insect jerking 

 its front legs back and forth. Both legs may be in motion at once, in- 

 dependently of each other, or one only may be waved about. Each leg 

 therefore stridulates without reference to the other, as Ranatra jerkily 

 moves it about in anger or excitement." 



