PS EONS: 
PLATES. 
Page. 
The transformation of the periodical Cicada ( Tibicen septendecim).....- - Frontispiece. 
isenee WOK orgthe periodienl Cicada: 22.0 cso ns BR ke 12 
Il. Photograph of chambers of the periodical Cicada, general view, 
taken-ate New Baltimore, Ni» Y.;,/May,, 18945 222 3222 se. 2 So 92 
III. Photograph of chambers of the periodical Cicada in woodshed, 
WieshinigtomsDe Cet 902 tsp estes teehee es eet 2 Sle noe 94 
IV. Chambers of the periodical Cicada, natural size, in woodshed, 
Washimeton,. Ds Civ 1002) pre: -- oaeh sare Aten so Jail: Sb be 96 
V. Empty pupal shells of the periodical Cicada clinging to leaves, 
Brocdixe 1902 Washington, D. Gre siseh. Jes. S25 2s. ee Dae 98 
VI. The transformation of the emerged periodical Cicada. .......-.-.- 100 
TEXT FIGURES. 
Fia. 1. The periodical Cicada, representing the typical form and dwarf form. . 21 
2. Map showing distribution of the broods of the 13-year race.......-...-- 36 
3. Map showing distribution of the broods of the 17-year race.........-.-. 37 
45,Map showine distribution of, Brood J, 1910... 22. 25-52... 92228-4225. 39 
5. Map showing distribution of Brood II, 1911........-. Laer. . Si aelw aes 40 
GME showine distribution, of Brood LIT, 912... 2. 2 een 22 ce y scaess eee 4] 
ie Mop showing distribution of Brood. TV, 1918... 2-22.22 t<ec -ncee Ss 42 
8. Map showing distribution of Brood V, 1914...........-...--.-: Fee as 44 
S.Map' showing distribution of Brood Vi, 1915. 52°.-.-. 2.2.5.2). .28622 5 45 
102) Map) showine distribution of Brood VIL, 191G_..2. ....-.- 22-42-2246 47 
iL Map showineidistribution of Brood VIIL, 1917 _....2....22 25. 22..,-45-2 48 
i> Map showing distribution..of. Brood. LX, 1918. 4.222222. 2. 2. sc -s2ae-%< 49 
i3Map showing distribution of Brood, xX, 1919)... 5... 5.5.22 252- sient 51 
ifo Map ciowine distribution of Brood XU, 1920... .- 025-2. n2 2 54 
15. Map showing distribution of Brood XII, 1921_...-. neat a hae Le eas ae te 56 
lé. Map showing distribution of Brood X11L).1922. 22. ..0.22 222225 2G222 22 57 
17. Map showing distribution of Brood XIV, 1923..........-......------- 59 
1S Map showing distribution)of Brood XV, 1907. ..-: 2. 22-22. s.4-54-1)5:=2 61 
19. Map showing distribution of Brood XVI, 1908 ..-...-..- 2. -...-+\--:- 62 
20 Map showing distribution of Brood XVII, 1909. -.........:.22..2...2: 63 
/ 21: Map showine distributionof Brood XVITE, 1919 =... 5..........0....<. 65 
22. Map showine distribution of Brood: XTX. 1907 2... 22s)... +e 66 
23. Map showing distribution of Brood XX, 1908.........-.-.....-------- 68 
24. Map showing distribution of Brood X XI, 1909................-------- 69 
25; Map showing distribution of Brood: XXII, 1910. ......-...<....-.------ 70 
26. Map showing distribution of Brood XXIII, 1941.2)... 2... sll en cil 
