INSECTS. HEMIPTERA. 



and the head prolonged into a long cylindrical snout, with 

 a longitudinal canal below for receiving the rostrum ; antennae 

 setaceous, inserted at the extremity of the rostrum, with the 

 third joint longest. 



The insects of this genus, like the others of the tribe, frequent the margins of 

 water, and run with quickness over its surface. They do not, however, swim, and 

 the silky down with which their bodies are covered protect them from the water. 



H. stagnorum, Lat. Body about five lines long, black or brownish 

 black, with the borders of the abdomen andthefeet reddish brown; 

 elytra short, with two nerves on each Lat. Gen. iii. 131. 



FAMILY II. HYDROCORIS.E. 



Antennae inserted under the eyes, concealed, and at most the 

 length of the head ; tarsi with at most two joints. 



The insects of this family are all aquatic, carnivorous, and seize with their ante- 

 rior feet other insects or animalcules for their food. Their antennae are never form- 

 ed of more than four joints. The head is sunk to the eyes in the thorax, and ap- 

 pears intimately united with it. The eyes are large, the rostrum short, and the 

 elytra horizontal. Their metamorphosis is the same as in the other Hemiptera. 



TRIBE I. NEPIDES. 



Anterior feet formed for seizing ; thighs large, with a furrow 

 below to receive the inferior margin of the leg ; tarsi short, 

 united at their origin with the legs, and forming together a 

 large hook ; body oval and much depressed, or linear. 



I. Anterior tarsi terminated by two hooks. 



Gen. GALGULUS. 



II. Anterior tarsi terminated simply in a point. 



1. Labrum large, triangular, covering the base of the rostrum ; no filaments, at least 

 very projecting, at the end of the abdomen. 



Gen. NAUCOB.IS. 



2. Labrum sheathed ; two filaments at the end of the abdomen. 



Gen. BELOSTOMA, NEPA, RANATRA. 



The anterior tarsi in the genera Ranatra and Nepa have but one joint ; in the 

 preceding genera they have two. The first joint of the four posterior tarsi is some- 

 times very short. From these characteristics Latreille thinks the tribe may be di- 

 vided otherwise, thus : I. All the tarsi with two joints, Galgulus, Naucoris, Belosto- 

 ma: 2. Anterior tarsi with a single joint, Nepa, Ranatra. 



Gen. NEPA, Lat. Lin. 



Legs and tarsi united to form a large hook which folds under 

 the thighs ; tarsi composed of a single joint ; antennae ap- 

 pearing forked ; body elliptic, very depressed ; head small, 

 lodged in part in a notch of the thorax ; scutellum large ; 

 abdomen terminated by two setaceous filaments ; four poste- 

 rior tarsi proper for swimming. 



N. cinerea, Lin. Body and elytra blackish brown or yellowish ; 

 abdomen broad, oval, very flat, red above ; scutellum large, trian- 

 gular ; anterior feet directed forwards. 8 or 9 lines long. In- 

 habits Europe, in stagnant waters Lat. Hist. xii. pi. 95, fig. 8. 



