HETERQPTERA. — NEPIDA. 461 
antennz are very short and variable in structure; they appear to be 
only 3-jointed in the typical species (fig. 119. 16. ant. of Ranatra, and 
see Curtis), whilst in Belostoma (fig. 119. 17.) and in Sphzrodema 
(Laporte, Hémipt. pl. 52. f.1.) they are 4-jointed, the middle joints 
being sometimes greatly developed on one side. The rostrum is a 
short but robust instrument, the labium being composed of three 
joints, and having on its front side, at the extremity of the second 
joint, a pair of oval lobes, first noticed by Savigny in Nepa (Mém. 
An. sans Vert. pl. 4. f. 3 6, and my fig. 119. 13. x). I have also ob- 
served them in several species of Ranatra, &c. (jig. 119. 12. x). Fig. 
119. 13. further exhibits the place of insertion of the slender mandi- 
bles and maxilla, which are here drawn out of their sheath (the 
labium), at the orifice represented dark in the basal joint (ana- 
logous to that represented in fig. 119. 4.), as well as the semicorneous 
tongue trifid in front, and having the pharyngeal orifice at its base. 
The description given by L. Dufour (Rech. Hemipt. pl. 6.. f. 81.) of 
these internal organs, is quite at variance with the account of Savigny; 
and all other authors. 
These insects are very predaceous, feeding upon other insects, espe- 
cially the larvee of Ephemere. Their motions are, however, very 
slow. The females of the typical genus deposit their eggs in the 
water ; they are of an oval form, and surmounted by seven elongated 
filaments (jig. 119. 14.), which serve, whilst the egg is in the oviduct, 
to form a kind of cup for the reception of the succeeding egg, but 
which are recurved when the egg is discharged. The eggs of the 
genus Ranatra are more elongated, and are furnished above with two 
slender sete. According to Rosel, they are deposited at random in the 
water, but Geoffroy states that they are introduced into the stems of 
aquatic plants, the elongated filaments being alone exposed. M. 
Dufour has described the eges deposited by two species of Naucoris, 
which differ considerably from those of Nepa and Ranatra. The fe- 
males of some species of Belostome carry their eggs upon their backs, 
arranging them in a single layer with great symmetry. The young 
insects resemble their parents, except that those which ultimately 
obtain elongated anal filaments have the body terminated at first by a 
short point (fig.119. 15. young larva of Nepa). Frisch, De Geer, 
Rosel, Swammerdam, and Geoffroy have illustrated the transforma- 
tions of the three genera found in England, whilst M. Dufour has 
elaborately detailed the anatomy of Nepa and Ranatra (Ann. Gén. de 
