50 THE PERIODICAL CICADA. 
series, of this Division. In 1897 its distribution in Ohio was very care- 
fully studied and mapped by Prof. F. M. Webster, and in West Vir- 
ginia by Prof. A. D. Hopkins. The distribution as listed below is 
based on Mr. Sehwarz's circular, with the additions noted by Messrs. 
Webster and Hopkins, together with such other localities as were 
reported to the Division by correspondents. 
Speaking of its relationships with other broods, Mr. Schwarz in the 
circular mentioned writes as follows : 
Brood XV is always preceded by one year by the 17-year Brood XIV, but this is 
known only from States west of the Mississippi River, so that no relationship seems 
to exist between these two broods. Brood XVI, which appears always one year later 
than Brood XV, is known from a number of localities both east and west of the ter- 
ritory occupied by Brood XV, but these localities are so scattered and of so small 
extent that no relationship between the two broods can be pointed out. Compari- 
sous with other 17-year broods are Aery tempting, but are, of course, mere specula- 
tion in the present state of onr knowledge. Still, can it be a mere coincidence that 
tbe territory occupied by Brood XX (1883-1900) is evidently a northeastward exten- 
sion of that occupied by Brood XV, or are geological reasons sufficient to explain 
the fact that the territory occupied by Brood XV almost exactly fills the gap between 
the two great divisions of Brood XXII (^885-1902)? 
The distribution, by States and counties, of this brood as now known 
is as follows : 
Ohio. — Athens, Ashland, Belmont, Carroll, Columbiana, Coshocton, Crawford, 
Cuyahoga, Erie, Fairfield, Franklin, Gallia, Geauga, Guernsey. Harrison, Hocking, 
Holmes, Huron, Jackson, Jefferson, Knox, Lake, Licking, Lorain, Mahoning, Medina, 
Meigs, Morgan, Monroe, Muskingum, Noble, Perry, Pickaway, Pine, Portage, Rich- 
land, Ross, Scioto, Stark, Summit, Tuscarawas, Vinton, Washington, Wayne. 
Pennsylvania. — Fayette, Washington. 
Virginia. — Highland (?). 
West Virginia. — Barbour, Boone, Brooke, Braxton, Calhoun, Clay, Doddridge, 
Fayette, Gilmer, Grant, Greenbrier (*), Hancock, Hardy, Harrison, Jackson, Kana- 
wha, Lewis, Marion, Marshall, Mason, Mineral, Monongalia, Nicholas, Ohio, Pleas- 
ants, Pocahontas, Preston, Putnam, Randolph, Ritchie, Roane, Summers ( ?). Taylor, 
Tucker, Tyler, Upshur, Wayne, Webster, Wetzel, Wirt, Wood. 
SYSTEMATIC POSITION AND STRUCTURAL DETAILS. 
The periodical Cicada belongs to the Homoptera, one of the two 
divisions of the Hemiptera, or great order of sucking insects, familiar to 
the public mind under the name of "bugs," and including, in addition 
to the graceful and attractive species like the Cicada, such foul-smelling 
spedes as the plant bugs, squash bugs, and certain animal parasites. 
The members of the suborder Homoptera, to which the Cicada and its 
allies belong, are, however, distinctly removed from the lower suborder 
of "bugs*' just referred to, namely, the Heteroptera, and lack the dis- 
gusting odor and habits, as a rule, of the latter and less esteemed sub- 
order of sucking insects. The Homoptera as a rule comprise clear- 
winged insects, which subsist on the juices of plants, and are active 
usually in flight and often beautiful in form and color. The Cicadas 
.are not only the largest and most striking insects of their suborder. 
