228 NATURAL SCIENCE [October 
the sudden appearance of a brood was believed to be the cause of a 
“kinde of pestilent feaver.” Records of the insect, during nearly 
two centuries, over the eastern and central States, have shown that 
there are two races, a northern with a seventeen-year, and a southern 
with a thirteen-year life-cycle. A number of broods of each race: 
have been registered, and their distribution being known, the future 
occurrences of the insect can be accurately forecast for the various 
districts. Careful observations of the larval and nymph stages have 
been made, and the changes undergone by the insect during its long 
underground life have been traced. | When development is com- 
plete the nymphs of a brood leave the ground almost simultaneously, 
and an alarming swarm of cicads is the result. The perfect insects 
live but a few weeks, and are believed to take no food. The female 
makes cuttings in tree-twigs wherein she deposits her eggs; the 
newly hatched larvae fall to the ground and burrow immediately. 
The injury caused by the cicads is almost confined to their egg-laying 
incisions ; though the larvae and nymphs suck sap from the roots of 
plants, their slow rate of growth and feeding prevents them from 
doing much damage. The life-cycle of this cicad is longer than that. 
of any known insect, but Mr Marlatt makes the probable suggestion 
that other larger species of the family might be found to have even 
longer larval stages, could the course of their generations be 
accurately followed. 
THE LARVA OF PELOPHILA 
In part 2 of the Zvransactions of the Entomological Society for the 
present year (pp. 133-140), Messrs W. F. Johnson and G. H. 
Carpenter make a contribution to the neglected subject of the life- 
history of the Coleoptera, by describing with figures the grub of the 
eround-beetle Pelophila borealis, which they have discovered in Ire- 
land. The larva agrees with those of the beetle’s nearest relations. 
—Nebria and Leistus—in possessing a pair of long, mobile cerci at 
the hinder end of the abdomen, apparently a primitive character. 
The head of the Pelophila grub, however, is broad and quadrate, and 
the legs short, contrasting with the rounded head with constricted neck 
and long legs of Nebria and Leistus, and in these respects reealling 
the structure of more generalised carabid larvae. 
FLAT-FISH oF SouTH AFRICA 
Mr J. D. F. Gincurist, who was recently appointed Marine Biologist 
to the Government of Cape Colony, is publishing in separate papers 
descriptions by various specialists of the material which he collects. 
These are entitled, “ Marine Investigations in South Africa. Depart- 
ment of Agriculture, Cape of Good Hope.” We have received a 
copy of a short paper on the Flat Fishes by Mr G. A. Boulenger. 
