566 



INSECTA. 



apart from the anterior, and twice as long as the body. [Common insects, often seen skimming' along the surface 

 of the water.] 



Velia, Latr., with the antennae also filiform, but with the sheath of the sucker only 2-jointed ; the legs mode- 

 rately long, and placed at equal distances apart. V. curretis, [a common British insect, seen running ou the 

 surface of brooks.] 



[The works of Laporte Comte de Castelnau, the Encyclopedie Methodique, Burmeister's Manual of 

 Entomology, vol. ii., Spinola's Essay on the Heteropterous Hemiptera, and Hahn's work, Die Wanzen- 

 artigen Insecten, must be consulted for many new genera established in this division of the order.] 



THE SECOND FAMILY OF THE HEMIPTERA,— 

 The Hydrocorise, or Water-bugs, — 



Has the antennae inserted beneath the eyes, by which they are concealed, being shorter than the head, 

 or scarcely longer than it. 



All these Hemiptera are aquatic and carnivorous, seizing other insects with their fore-legs, which 

 fold upon themselves, and serve them as claws. They prick very sharply [with the proboscis]. The 

 tarsi have only one or two joints ; the eyes are generally of a remarkable size. 



Some of the Hydrocorisse, forming the subfamily Nepides, have the two fore-legs formed into claws 

 composed of a very thick or very long thigh, channelled on the under side to receive the under surface 

 of the tibia and of the tarsus, which is very short, or is united with the tibia, forming with it a strong 

 hook ; the body is oval and very depressed in some, and of a hnear form in others. These insects form 

 the genus 



Nepa, Linn., — 

 Which may be thus divided : — 



Galgulus, Latr., in which all the tarsi are alike cylindrical, with two distinct joints, the last of which is furnished 

 with two hooks at the tip ; the antennae appear to have only three joints, the last of which is large and ovoid. 

 {Naucoris oculata, Fab. ; North America.) 



The antennae in the following genera are composed of four joints, and the anterior tarsi are terminated simply 

 in a point, or by a hook. 



Naucoris, Geoff., has the labrum exposed, large, and triangular ; the body is nearly oval and subdepressed ; the 

 eyes flattened ; the extremity of the body is not furnished with elongated processes ; the four hind feet are ciliated 

 with 2-jointed tarsi, and two ungues at the tip. N. cimicoides, Linn., [a common British insect, half an inch long]. 

 In the three following subgenera, the labrum is hidden in the canal, and the extremity of the abdomen furnished 

 with two filaments. 

 Belostoma, Latr., has all the tarsi 2-jointed, and the antennae semi-pectinated. [Exotic species.] 

 Nepa, Latr., has the fore tarsi formed of a single joint, and the four hind tarsi 2-jointed ; the antennae appear 

 forked ; the fore coxae are long, and the thighs thicker than the other parts. The abdomen 

 is terminated by two long filaments, which are employed in respiration ; the eggs resemble 

 the seed of some plant, being oval, surmounted by a coronet of hairs. M. L. Dufour has 

 published an elaborate memoir on their internal anatomy. N. cinerea, Linn., of a dirty 

 ash-colour, with the upper surface of the abdomen bright red, [is a very common insect.] 



Ranatra, Fabr., differs from Nepa in its linear form, and the more elongated form of the 

 legs. JV. linearis, Linn, [a common British species in certain localities]. The coronet at 

 the top of its eggs is formed of only two threads. 



The others, Notonectides, have the two fore-legs simply incurved, with the thighs 



of the ordinary size ; the tarsi diminishing to a point, and very much cihated or 



similar to the others ; the body is nearly cylindric or ovoid, and rather thick, or not 



so much depressed as in the preceding ; the hind legs are very much ciliated, in 



the form of oars, and terminated by two very minute claws : they swim or row 



with great quickness, and often on their backs, [whence their generic name]. They 



compose the genus 



NoTONECTA, Linn., — 

 Which may be thus divided : — 



Corixa, Geoff., which has no scutellum, the elytra horizontal ; the fore-legs very short, with 

 the tarsi composed of a single compressed and ciliated joint ; the other legs are elongate, and 

 the two middle ones terminated by two very long ungues. N. striata, Linn, [and several other 

 small British species]. 



Sigara, Leach, founded upon N. mimitissima, Fabr., has the fore-tarsi 1-jointed, but possesses 

 a distinct scutellum, and the body ovoid. 



Notonecta, Linn., has a distinct scutellum ; a rostrum elongate-conic ; the wing-covers de- 

 flexed at the sides, and all the tarsi 2-jointed ; the fore tarsi are cylindric, simple, and terminated by two ungues. 



Kig. 97. — Nepa cinerea. 



fig. ya— N. gla 



