HEMIPTEEA. 99 



pointed bristles. Two present on one side a sort of narrow sharp 

 blade, and have teeth towards their base. Of the two others, the 

 pne is a thin smooth needle, the other is provided with hairs 

 directed backwards and forwards. 



It is with this rostrum, which resembles a case of surgical in- 

 struments, that the Nepa bites and sucks little aquatic insects, not 

 even sparing its own species. Its bite is painful to man, but 

 not in the least dangerous. With its four hind legs the Nepa 

 swims, but at a very slow pace. It generally drags itself along 

 the bottom of the water, on the mud, and does not avoid the 

 hand put out to seize it. Its body is terminated by a tail, composed 

 of two grooved threads, which, when applied together, form a tube, 

 capable of being moved from side to side. Through this canal it 

 breathes the outer air ; it puts the end of it out of the water, and 

 the air enters it by inspiration. Some very small hairs, with 

 which the interiors of the grooves are lined, interlace each other, 

 and prevent the water from penetrating into the canal. It is 

 probable that this same canal serves also for depositing the eggs. 

 These last resemble small seeds, covered with points, and are 

 buried in the stalks of aquatic plants. 



Next to the Nepa comes the Ranatra, with a cylindrical, elon- 

 gated, linear body, with very long and very thin hind legs, and of 

 which one species, which Geoffrey 

 calls the " aquatic scorpion with an 

 elongated body," is common every- 

 where in stagnant waters in spring. 

 It is brownish, carnivorous, and very 

 voracious. 



We must now mention the genus 

 Corixa, of which one species, the 

 Corixa striata, is very common. 

 This insect walks badly and slowly 



on land, but swims and cuts through the water with a prodigious 

 rapidity. 



However, it is not to delay over this last species that we have here 

 written the name of this genus. Some insects which belong to it, 

 and which are found in Mexico, deserve to be mentioned, on account 

 of certain peculiarities which their eggs present. A naturalist, 



H2 



