110 



NATURAL HISTORY. 



FAMILY XL NEPID^, OR WATER SCORPIONS. 



In this family the ocelli are wanting, the antennae are either three- or four-jointed, the body 

 is flat above, elliptical or much elongated, and the hemelytra are furnished with a distinct membrane. 

 The rostrum is of three joints. The fore legs in all are raptorial ; the remainder are either simple, 

 fringed, or flattened, but in all case.s are used as swimming organs. All the species live in the 

 water and prey upon their weaker fellows. They are, however, well furnished with wings, and 

 can fly readily, a provision which is useful in case of any need arising for seeking a new abode. 



The common Water Scorpion (Nepa cinerea) is a very well-known aquatic insect, and is abundant 

 in the fresh waters of all parts of Europe. It is about an inch long, elliptical, yellowish-grey, with the 



back of the abdo- 

 men red ; the an- 

 tennse have three 

 joints ; the hinder 

 legs are scarcely 

 fringed, and have 

 tarsi of a single 

 joint ; and the body 

 is terminated by a 

 pair of tail-like or- 

 gans, which, when 

 put together, form a 

 breathing tube. The 

 insect is sluggish in 

 its movements. The 

 female attaches her 

 eggs to water plants. 

 They have at the 

 upper end seven 

 radiating processes. 

 The Ranatrce, which 

 resemble the pre- 

 ceding in the char- 

 acters of the an- 

 tenna?, tarsi, and 

 air-tube, have a 

 They have the fore 



RANATRA LINEARIS AND NEPA CINEREA. 



very elongated body, whence the British species is called Itanatra linearis. 

 legs much lengthened, and the four hinder tibiae rather more fringed than in Nepa. 



Another division of the family having four-jointed antennae, two-jointed hinder tarsi, and no 

 breathing tube, is represented in Britain by a small oval species, about half an inch long, of an olive 

 brown tint, known as Naucoris cimicoides. It has a broad, deeply-immersed head ; the anterior tarsi 

 consist of a single joint ; and the hinder tibiae and tarsi are fringed, so that the insect is a more active 

 swimmer than the Water Scorpion. When handled it is able to inflict a painful wound. Some of 

 the exotic allies of this species are among the giants of the order, or indeed of the insect world. Thus 

 the Belostoma grande, a native of South America, measures over four inches in length. This must be 

 a most formidable enemy to the weaker inhabitants of the fresh waters of Brazil and Guiana, as besides 

 its large size, it is favoured by having the hinder legs widened into regular paddles, which must 

 enable it to swim with great rapidity. Other allied species of nearly equal size occur in the tropical 

 parts of both hemispheres. The females of some of the smaller tropical forms (Diplonychus, &c.) 

 deposit their eggs close together upon their backs, and thus carry them about. 



FAMILY XII. NOTONECTIUJE. 



The Notonectidse have a bi-oad head with the forehead rounded and turned down, so that the in- 

 sertion of the rostrum is brought close to the anterior margin of the sternum. The body is convex 



