( Ixxiii ) 
divergence is associated with the differing haunts and habits 
of the two forms. Mr. Marshall seems inclined to the view 
that the wet-season form octavia-natalensis is the older one, 
and that the dry-season form sesamus, with its distinctly 
protective underside, may be the result of greater persecution 
—in the scarcity of insects of other orders—during that 
season. On the other hand, he suggests the possibility of 
the wet-season natalensis-form being in process of modification 
in mimicry of the prevalent red black-spotted Acree of the 
same region ; in which case sesamus would have to be taken 
as the older form. I consider the latter to be more likely 
than the former view, seeing how much less seswmus has 
diverged than octavia-natalensis from the general pattern of 
the genus Precis.* 
A noteworthy fact in Mr. Marshall’s experience in this 
case was that, while in the second instance recorded he 
reared an example of sesamus from an egg laid by octavia- 
natalensis, he also obtained, only five days later, from another 
egg laid by the same mother, on the same day, a pure 
octavia-natalensis. He expressly states that the two larve from 
“which these amazingly different butterflies resulted were 
reared from the egg under precisely similar conditions ; and 
he adds that not a few similar instances had come under his 
notice. This is sufficiently remarkable, but it by no means 
exhibits the apparent extreme of variation among the off- 
spring of one mother; for Mr. de Nicéville (in a letter 
of 13th June last) assures me that in India “at the change 
of the season, in one brood, from one batch of eggs laid by 
one female, you sometimes get both seasonal forms and all 
intermediate ones.”? Such cases, like those of more or less 
* The only other species of Precis of the octavia pattern and colouring 
is P. simia (considered by Mr. Marshall to be the wet-season form of the 
dry-season P, cwama) and this species may possibly also be mimetic of the 
Acree. 
+ It would be of the very greatest service to these inquiries if such a 
series as this, the offspring of one mother, could be preserved in its 
entirety, together with a full record of all the conditions bearing on the 
case. Mr. de Nicéville does not mention the actual species to which his 
remark applies. 
