THK DWAKK KOKM 
21 
to consider tliis sinnll form ns n wwio xaruMy or, in()i-(» properly, a 
(liniorphic variedly iA' the lnrij:(M' form. 
On (lit^ autlu)i"ily oi' \arioiis o1)S(M"\'(M-s (-(Miain (liNcrLrcncc-. in liaMis 
l)ot\\(HMi lli(> (wo t'oI•|U-^ wcvc coiuiiKMUcd iipoii. Il sccincd (o he llic 
tj^eiuM'al Ixdirl' llial thi^ lari^iM- one appears soiiu'wliat cai'licM', fioiii 
ci0\l to ten days, and corrc^sixjndinixly, also, the sniall(M- form disap- 
p(Mirs sonu'wlial lahM'in \\\c s(\ison than the lar^M'r. Tlie smaller 
cicadas were also I'cportcd by \'ari()ns ()l)s(>r\(»i"s as bcin*:; moi'c or less 
<i:re*j:arioiis in habit, not always intermin<j:linu: with the larirer oncvs but. 
colU^ctini:; in snu-dl (•om[)ani(\s in orchards or in thickets alon<: sti'(>ains 
and moist })lac(v^. Furtber, tbe son^^ note of the small form was 
somewhat diH'cMHMit . l)ut this last variation was not fully confirmed. 
Tliis small Cicada was particularly n()t(>d in the case of I^i'ood X 
at the time it was studied by 
Walsh and Kiley in 1S6S and, 
judirini2: from the records ob- 
tained of this brood of 1885 
and 1902, Brood X seems to 
be its ])articular strongliold, 
although it occurs witli other 
broods, often ver}" scatter- 
In 1 002 the writer observed 
this small form in great abun- 
dance in and near the District 
of Cohnnbia, but, contrary to 
the former l)elief, it appeared 
in larg(^ pei'cc^ntagc^ during 
the first week or ten days of 
the emergence of the Cicada, 
])r()l)al)ly repr(>s(>nt ing 50 per 
cent of the specimens, and soon disappeared. Both sexes were rep- 
resented, and mating and oviposit ion seemed to go on normally as 
witli the large form. The song notes of the dwarf Cicada were dis- 
tinctly different from the common note of the large Cicada, namely, 
a broken and chirping note, very shrill and loud. The abundance 
of the small form in 1902 and \]\v difference in its song notes were 
observed by various persons throughout the range of the brood. 
A careful statistical study of the variation in size and character- 
istics of the large and small for-ms ^\•as made in connection with the 
1902 appearance of this brood in Ohio by Prof. Herbert Osljorn.'* 
Professor Osborn examined and made careful measurements of some 
800 specimens taken at random from various localities. The results 
Fig. 1.— The periodical Cicadca: A, male of typical 
form, natural size; c, d, genital hooks enlarged; g, 
singing apparatus, natural size: B, male of the small 
form (ca.s.sznu'), natural size; e,f, genital hooks, en- 
larged. (After Ril(>y and Hagen.) 
"Ohio Xaiiiralisi. III. pp. :',_':i i'.i'd, \h-ci- 
