SEVENTEEN- YEAR LOCUST — SNODGRASS. 405 
once commences it proceeds very rapidly through the whole nest, 
showing that the eggs are all at the bursting point when the rupture 
of the first takes place. 
In each lateral compartment of an egg nest the eggs (pi. 4, E 
and F) stand in two rows with their lower or head ends slanted to- 
ward the door. (It must be remembered that the punctures are made 
on the lower sides of the twigs, so that the eggs are inverted in their 
natural position in the nests.) On hatching, each egg splits vertically 
over the head and about one-third of the length along the back, but 
for only a short distance on the ventral side. As soon as this rupture 
opens the head of the young cicada bulges out, and then, by a bending 
of the body back and forth, the creature slowly works its way out of 
the shell, which, when empty, remains behind in its original place. 
The nymphs nearest the door have an easy exit, but those from the 
depths of the cell find themselves still in a confined space between the 
projecting ends of the empty shells ahead of them and the chamber 
wall, a passage almost as narrow as the egg itself, through which the 
delicate creatures must squirm to freedom. 
Now, a newly hatched Orthopteron, or a newly hatched or newly 
bom aphid, is done up in a tight-fitting garment with neither sleeves 
nor legs, and a young grasshopper hatching under the ground has a 
difficult journe}^ to the surface. But nature has been more con- 
siderate in the case of the young cicada. It, too, comes out of the 
egg clothed in a skin-tight jacket, but this garment is not a mere bag, 
as with the other insects mentioned. Each is provided with special 
pouches for the appendages, or a part of them (fig. 8, £). The 
incased antennae and the labrum project backward as three small 
points lying against the breast. The front legs are free to the bases 
of the femora, though so tightly held in their narrow sleeves that 
their joints have no independent motion. The middle and hind legs 
are also incased in long, slim sheathes, but they alwaj^s adhere close 
to the sides of the body. Thus the creature newly hatched much 
resembles a tiny fish provided only with two sets of ventral fins, but 
when it gets into action its motions are comparable with the clumsy 
flopping of a seal stranded on the beach and trying to get back into 
the water (fig. 8,3). 
The infant cicada knows it is not destined to spend its life in the 
narrow cavern of its birth, or at least it has no desire to do so. 
With its head pointed toward the exit, it begins at once contortion- 
istic bendings of the body, which slowly drive it forward. By 
throwing the head and thorax back the antennal tips and the front 
legs are made to project so that their points may take hold on any 
irregularity in the path. Then a contractile wave running forward 
through the abdomen brings up the rear parts of the body as the 
12573° — 21 27 
