SYSTEMATIC POSITION AND STRUCTURAL DETAILS. 
51 
some of the species measuring over o* inches in expanse of wings, but 
in the male sex are endowed with the power of song, which last char- 
acteristic has invested them with great popular interest in all ages; and 
especially in the poetry of nature are they noteworthy, from the time of 
Homer to the present. 
The old genus Cicada is represented by species in all parts of the 
world, over 500 distinct forms being already known, and they are 
especially abundant in North America, nearly 100 species having been 
described from the continent and adjacent islands. The more familiar 
of these insects to the popular mind are the common Dog-day Cicadas, 
or Harvest Flies, represented by several species, the most abundant of 
which is perhaps Cicada pruinosa (tibicen). The sleepy droning of these 
annually appearing species in July and August is commonly taken as a 
harbinger of greater 
heat, and is a most fa- 
miliar characteristic of 
midsummer. 
The periodical spe- 
cies is much more slen- 
der and graceful than 
the majority of the an- 
nual visitors, but struc- 
turally is not very dis- 
similar. It is medium 
sized, for the most part 
black in color, with 
orange-red eyes and 
limbs, and with the 
margin of principal 
veins of the four nearly 
transparent wings sim- 
ilarly colored. 
In discussing the 
structure of this insect 
particular attention 
will be given only to 
the important organs, viz, those for taking food, or the beak: the 
instrument for piercing plants and depositing eggs, or the ovipositor; 
and the organ of song in the male insect. 
A cursory examination of one of these insects from above reveals its 
rather robust body, covered by two pairs of transparent parchment 
like elliptical wings, which rest roof-like over the abdomen: the short 
transverse head with great oval prominent eyes at the lateral angles, 
the three minute ocelli arranged in a triangle on top, and the very 
short, thread-like antenna) projecting between the compound eyes. 
Viewed from beneath, the triangular prolongation of the head into the 
Fig. 20. — Head and prothorax of Cicada, lateral view, showing 
parts in normal position— tor description, see fig. 22 (author's 
illustration). 
