460 MODERN CLASSIFICATION OF INSECTS. 
The middle legs are slender, and armed with remarkably long and 
slender claws, whilst the hind legs are long, with the two tarsal joints 
very broad, ciliated, and well adapted for swimming. The same struc- 
ture exists in the larve of this genus, except that I cannot perceive 
any trace of articulation in the hind tarsi, which consist of a single 
joint. I have observed great numbers of these insects of different 
species congregated and huddled together at the surface of the water 
beneath the ice when frozen ; many of them had hold of each other, 
and they appeared very inactive. The species of this family are 
widely distributed, and are found in almost all parts of the world. 
The exotic species require a minute revision, being (as evidently 
proved by our British species) extremely variable in their markings. 

The second family, Nepipm*, has the body depressed (fig. 119. 10. 
Nepa cinerea) ; the head small, with large lateral eyes; the fore legs 
strongly raptorial, having the coxz very long; the thighs dilated, with 
a notch along the inner edge to receive the tibia, which is curved and 
united with the tarsus (jig. 119. 11.), composed of a single joint, or- 
dinarily without ungues }; the two other pairs of feet are alike in 
structure, and formed for creeping amongst the roots of aquatic 
plants, with 2-jointed tarsi, furnished with two ungues. The ex- 
tremity of the body in the typical species is furnished with two long 
and slender filaments, the use of which has been noticed above. The 

* Bristiocr. Rerer. To THE Nepripa. 
The general works of Spinola, Burmeister, Laporte, Dufour, Zetterstedt, Fallen, Fa- 
bricius, and others upon the entire order. 
+ The structure of the fore legs of Ranatra has much puzzled some authors: 
thus Geoffroy mistook them for antennae, whilst Mr. Curtis considers that the 
femur and tibia are united with a strong tooth on the inside at their union, and 
terminated by a two-jointed tarsus. Analogy with such genera as Mantis, or even 
Nepa, is sufficient to show the incorrectness of this description, and that the tooth 
on the under side of the limb indicates that part of the femur which acts in concert 
with the tip of the raptorial tibia. Latreille and Savigny more philosophically de- 
seribed this “ crochet terminal,” as “ formé de la jambe et du tarse réunies.” (M/ém. 
An. sans Vert. p. 60.) 
