The Ohio iJSCaturalist, 



PUBLISHED BY 



The Biological Club of the Ohio State Uni'versily. 

 Volume III, DECEMBER, 1902. No. 2. 



TABLE OF CONTENTS 



OSBORX— A Statistical Study of Variations in tlie Periodical Cicada 323 



SCHAFFNER— Oijservations on Self-Pruning and tlic Formation of Cleavage 



Planes 327 



OsBORN— Note on the Occnrence of the Cigarette Beetle in Columbus 3:!0 



SCHAFFNER— The Flora of Little Chicken Island 331 



Burr— Compass Plants of Ohio 333 



SiMKiNS — A Record of 0))servatious on the Dandelion 334 



Mills— Prehistoric Anthropology 336 



A STATISTICAL STUDY OF VARIATIONS IN 

 THE PERIODICAL CICADA.* 



Herbert Osborn. 



One principal variation from the normal type of Tibicen septeiii 

 decern has been recognized at least since 1829. It VA^as described 

 as a distinct species in 1857, but later Rileyf and other authors 

 have given it varietal rank only, and jNIarlatt in iSqSJ' terms it a 

 "dimorphic variety." 



In the occurrence of the present 3'ear this form has been very 

 abundant at Columbus and elsewhere, and I have thought it 

 niisfht 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 b3^, from Arlington to the west and Franklin Park 

 to the east of the oxiy , representing points about eight miles 

 apart, and other lots in Cincinnati and at Brush Lake. Observa- 

 tions have been reported to me b}- 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 entireh^ black, only rare specimens showing a narrow 

 hind ])order of yellowish or orange 3^ellow. The cross \-eins 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 i, IQ02. 

 t Inj. & Ben. Ins., Rep. Mo, i, p. 20. 

 1 Bull. 14, Div. Ent., p. 17. 



