DIMORPHISM. 655 
ants and bees, a distinct form so as to be readily recog- 
nized at first sight. Among the Celenterates and worms 
the forms reproducing by parthenogenesis are usually larval 
or immature, as if they were prematurely hurried into ex- 
istence, and their reproductive organs had been elaborated 
in advance of other systems of organs, for the hasty, sud- 
den production, so to speak, of large numbers of individu- 
als like themselves. 
In insects, as we have stated elsewhere,* dimorphism is 
intimately connected with agamic reproduction. Thus the 
summer wingless, asexual Aphis and the perfect winged 
autumnal Aphis may be called dimorphic forms. The per- 
fect female may assume two forms, so much so as to be mis- 
taken for two distinct species. Thus, an oak gall-fly (Cy- 
nips guercus-spongifica) occurs in male and female broods in 
the spring, while the autumnal brood of females were de- 
scribed originally as a separate species under the name 0. 
aciculata. Walsh considered the two sets of females as di- 
morphic forms, and that Cynips aciculata lays eggs which 
produce C. guercus spongifica. Among butterflies, dimor- 
phism occurs. Papilio memnon has two kinds of females, 
one being tailless, like the tailless male, while Papilio Pam- 
mon is polymorphic, there being three kinds of females be- 
sides the male. 
There are also four forms of Papilio Ajaz, the three 
others being originally described as distinct species under 
the name of P. Marcellus, P. Telamonides, and P. Walshit. 
Our Papilio glaucus is now known to be a dark, dimorphic, 
climatic form of the common Papilio Turnus. There are 
dimorphic males among certain beetles, as in the Golofa 
hastata Dejean, of Mexico, in which one set of males are 
large and have a very large erect horn on the prothorax, 
and in the other the body is much smaller, with a very 
short conical horn. 
Temperature is also associated with the production of 
polymorphic forms in the temperate regions of the earth, 
as seen in certain butterflies, southern forms being varieties 
* Quide to the Study of Insects, sixth edition, p. 52. 
