THE DWARF FORM. 21 
to consider this small form as a mere variety or, more properly, a 
dimorphic variety of the larger form. 
On the authority of various observers certain divergences in habits 
between the two forms were commented upon. It seemed to be the 
general belief that the larger one appears somewhat earlier, from 
eight to ten days, and correspondingly, also, the smaller form disap- 
pears somewhat later in the season than the larger. The smailer 
cicadas were also reported by various observers as being more or less 
gregarious in habit, not always intermingling with the larger ones but 
collecting in small companies in orchards or in thickets along streams 
and moist places. Further, the song note of the small form was 
somewhat different, but this last variation was not fully confirmed. 
This small Cicada was particularly noted in the case of Brood X 
at the time it was studied by 
Walsh and Riley in 1868 and, 
judging from the records ob- 
tained of this brood of 1885 
and 1902, Brood X seems to 
be its particular stronghold, 
although it occurs with other 
broods, often very scatter- 
ingly. 
In 1902 the writer observed 
this small form in great abun- 
dance in and near the District 
of Columbia, but, contrary to 
the former belief, it appeared 
Fig. 1.—The periodical Cicada: A, male of typical 
nm large percentage during form, natural size; c, d, genital hooks enlarged; g, 
the first week or ten days of singing apparatus, natural size: B, male of the small 
the emergence of the Cicada, ney Netter Biles ona Hoses je ad 
probably representing 50 per 
cent of the specimens, and soon disappeared. Both sexes were rep- 
resented, and mating and oviposition seemed to go on normally as 
with 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 the 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 forms was made in connection with the 
1902 appearance of this brood in Ohio by Prof. Herbert) Osborn. ¢ 
Professor Osborn examined and made careful measurements of some 
800 specimens taken at random from various localities. The results 
@QOhio Naturalist, III, pp. 323-326, December, 1902. 
