462 MODERN CLASSIFICATION OF INSECTS. 
Scienc. Physig. Brux. tom. vii. and Recherch. Hemipt.). The last-named 
genus is remarkably elongated, with very long and slender feet and 
anal filaments. Like the rest of the family, itis able, when disposed, 
to leave the water and take wing. I have seen one descend into a 
pond, when it had the greatest difficulty to immerge itself, owing to 
the dryness of the anal filaments; at the same time I noticed that it 
did not move its four hind legs in concert. The other British genus 
Naucoris is especially interesting in the arrangement of the order, 
from its more perfect powers of swimming, the four hind legs being 
well fitted for this action; in this respect, as well as in the breadth of 
the head, approaching the Notonectide ; but the fore legs( jig. 119. 18.) 
are more perfectly raptorial than in any of the other Nepide, the 
femora being greatly dilated. In the Crochard edition of the Regne 
Animal (Ins. pl. 93. f. 5. c), this leg is described and figured as wanting 
the anterior tarsus, but this part clearly exists; the rostrum is short 
(fig. 120. 1.). The genus Belostoma comprises some of the most 
gigantic species of this order, being three inches long. These are 
peculiar to the waters of the tropics: their ovate depressed form, and 
the more natatorial structure of the hind feet, fits them better for swim- 
ming than the Nepe and Ranatre. The fore feet of the large species 
are peculiar, having the tarsi distinctly 2-jointed, but quite incorpo- 
rated with the extremity of the tibiae, and terminated by a long, slender, 
and acute unguis.* In some of the smaller species (G. Diplonychus 
Lap.), there are two short ungues in the anterior tarsi, which are 
more distinct, and they are also furnished with a short basal (3d) joint 
easily visible from beneath. 
The second section of the order has been named Geocorisa by 
Latreille, the greater number of the species being terrestrial ; some, 
however, are found upon the surface of water; and hence these, al- 
though closely allied in general structure to the other Geocorisa, 
have, on that account, been separated by L. Dufour into a distinct 
* In the larva the fore feet are terminated by two ungues. M. Spinola also 
states that the males of the large Brasilian species B. grandis have also two ungues. 
He also asserts that the male Belostome and both sexes of Sphwrodema have the 
ordinary organs of respiration ; whereas in the female Belostome the spiracles of the 
abdomen (except the last pair) are obsolete; and further, that the two anal ap- 
pendages of this genus are in no wise employed in the act of respiration. (Rev. 
Zool. Soc. Cuvierr. 1839, p. 112.) It is on this account that Spinola has separated 
the Nepides as a distinct primary tribe of the order from the rest of the Hydrocorizes. 
