ARTICULATA. 187 
being very different from that of C. septendecim. The body is robust, the 
head large and triangular, with three stemmata, the eyes prominent, the 
antenn short and thin, with six articulations, and the wings are large, and 
generally transparent. 
The history of Cicada septendecum, known in the United States as the 
seventeen year locust, has been given in a valuable pamphlet by Dr. Potter, 
of Baltimore, who, deceived by the popular name, fancied that anything 
called docust must belong to the genus Locusta, and he accordingly names 
the insect Locusta Septentrionalis Americane decem septima, confounding 
these hemiptera with the grasshoppers, and naming the latter Czcada. 
Vernacular names being entirely independent of the scientific ones, 
attempts to make them correspond generally result in confusion. Dr. 
Harris gives some useful details in his Injurious Insects of Massachusetts, 
and Dr. 8. P. Hildreth has written upon it in Silliman’s Journal, vol. xviii. 
p. 47, and 2d Series, vol. iii. p. 216. See also vol. xiii. p. 224. The pupa ot 
this insect leaves the ground in the Southern States in February and March, 
in Pennsylvania in May, and in Massachusetts in June. The female cuts 
openings with her ovipositor in the tender branches of trees, where her 
eggs are inserted; this causes the branches to die, and one observer relates 
an instance in which “the tops of the forests for upwards of a hundred 
miles appeared as if scorched by fire.” It requires fifty-two days for the 
young to hatch, when they immediately precipitate themselves to the 
ground, which they enter and attack the roots, the juices of which they 
suck. Miss M. A. Morris (Proceed. Acad. Nat. Sci., vol. iv. pp. 132 and 
190) has ascertained that these larvee do much damage to fruit trees by 
their attacks upon the roots. She found them in great numbers upon all 
the roots which were more than six inches beneath the surface, and the 
trees were evidently suffering under their attacks. The larvee were firmly 
attached to the roots by the insertion of their rostrum, and inclosed in a 
compact cell of clay without outlet, rendering it probable that they are 
sedentary where they first attach themselves. According to Miss Morris, 
they are destroyed by moles. The anterior feet of the larva and pupa are 
robust and adapted for digging, but those of the imago do not exhibit this 
character. 
Fram. 8. Notonectide (pl. 80, figs. 72, 73). This family of small preda- 
ceous insects is named from the habit which the species have of swimming 
with the back below. They are aquatic, the head and eyes are large, 
the antennz small, with four articulations, and the posterior feet are long 
and fringed, held out in repose like a pair of oars, and used like them in 
swimming. They are able to fly from one piece of water to another. 
Corixa striata ( pl. 80, fig. 72 ab); Notonecta glauca (fig. 78). 
Fam. 9. Nepide (pl. 80, figs. 68-71). This family is predaceous and 
aquatic, the species living at the bottom of quiet waters. The body is 
generally depressed, the antennze about as long as -the head, and inserted 
below the eyes so as to be hidden. The tarsi are dimerous, and the 
anterior feet raptorial. Ranatra linearis (fig. 68); Nepa cinerea (fig. 
69); Waweoris cimicordes (fig. 10); Belostoma (fig. 71). The last genus 
391 
