The Ohio £J\ Naturalist , 
PUBLISHED BY 
The Biological Club of the Ohio State University. 
Volume III, DECEMBER, 1902. No. 2. 
TABLE OF CONTENTS 
Osbokn — A Statistical Study of Variations in the Periodical Cicada 323 
Schaffnf.r — Observations on Self-Pruning and the Formation of Cleavage 
Planes 327 
Osborn— Note on the Occurence of the Cigarette Beetle in Columbus 330 
Schaffner — The Flora of Little Chicken Island 331 
Burr — Compass Plants of Ohio 333 
Simkins — A Record of Observations on the Dandelion 334 
Mills— P rehistoric Anthropology 336 
A STATISTICAL STUDY OF VARIATIONS IN 
THE PERIODICAL CICADA * 
Herbert Osborn. 
One principal variation from the normal type of Tibicen septem 
decern lias been recognized at least since 1829. It was described 
as a distinct species in 1857, but later Rileyf and other authors 
have given it varietal rank only, and Marlatt in 1898^ terms it a 
‘ ' dimorphic variety. ’ ’ 
In the occurrence of the present year this form has been very 
abundant at Columbus and elsewhere, and I have thought it 
might be worth while to secure some statistical data as to it and 
to review briefly the question of its relation to the typical form. 
Material has been collected from the University grounds and 
timber near by, from Arlington to the west and Franklin Park 
to the east of the city, representing points about eight miles 
apart, and other lots in Cincinnati and at Brush Lake. Observa- 
tions have been reported to me by Mr. Dury and Professor Geyer, of 
Cincinnati, and from Prof. Cook, of DePauw University, Green- 
castle, Ind. These specimens and observations have been cor- 
roborative of my own and need not be further mentioned, except 
when included with precise measurements. 
The cassini form is smaller than the normal and the abdomen 
beneath is entirely black, only rare specimens showing a narrow 
hind border of yellowish or orange yellow. The cross veins of 
the wing forming the “W” mark are commonly less oblique and 
the “W” therefore shortened. This point, however, as in the 
Read before Section F, Am. Assoc. Adv. Science, Pittsburg, July 1, 1002. 
t Inj. & Ben. Ins., Rep. Mo, 1, p. 20. 
t Bull. 14, Div. Ent., p. 17. 
