POLYMORPHIC BUTTERFLY. 259 
manent form and has admirably traced the relations of each form 
to the others. The account given below is almost entirely based 
on his observations. 
_No histories of butterflies are of deeper interest than those of 
polymorphic species, whether considered in themselves alone or 
in the light they are destined to throw upon the origin of species 
and races, problems which demand the profoundest thought and 
most conscientious investigation ; and since this species is poly- 
morphic in a larger sense than any other American butterfly is 
known to be, our interest is greatly enhanced. 
_As hinted above, Ajax appears under three different forms — 
Walshii, Telamonides and Marcellus, the polymorphism affecting 
both sexes equally. These forms are shown by Mr. Edwards to 
produce one another in a complicated manner, but in general the 
imago exhibits what has been termed seasonal polymorphism ; 
that is, a series of individuals adhering, in all their variations, to 
several distinct types, each type appearing at a different season 
of the year from the others ; thus Walshii is the early spring type, 
Telamonides the late spring, and Marcellus the summer and autumn 
type. Nearly all the butterflies which, in West Virginia, emerge 
from the chrysalis before the middle of April are Walshii ; between’ 
that and the end of May, Telamonides; after this, Marcellus. 
The first two, however, do not appear properly to represent distinct 
broods; and this point (to which Mr. Edwards has failed to draw 
special attention) is one of the most extraordinary features in the 
history of the insect ; for Telamonides, judging from his recorded 
observations, is not the direct conseasonal produce of Walshii, 
ut both are solely made up of butterflies which have wintered as 
chrysalides, those which disclose their inmates earliest producing 
Walshii, the others, Telamonides ; while all butterflies- produced 
from eggs of the same season—and there are several successive 
broods —belong to Marcellus. Thus, besides the true seasonal 
dimorphism which distinguishes the butterflies produced from eggs 
of the same season from those derived from eggs of the previous 
Season, we have a secondary seasonal dimorphism, as it may well © 
be called, separating the earlier from the later produce of wintering 
chrysalides. 
_ Mr. Edwards has also proved by his experiments that a portion 
of every brood of chrysalides, instead of disclosing the imago at 
the end of the ordinary time, retain it, occasionally until the ap- 
