group of Butterflies, Potaro District, British Guiana, 421 
It will be noticed there are only three examples 
exhibiting a wholly obscured band on the under-side. 
Two of these are of males and one a female. All three 
have the extreme dark upper-side as well. Those put in 
the “partly obscured” category are examples showing a 
great contraction of the fulvous band by an extension 
of the black inwards from the outer margin. It, again, 
in this species is evident that on the under-side a wholly 
black area is the exception and not the rule while on 
the upper-side nearly half (44 °/) the individuals are of 
the extreme black form. Again, looked at from another 
point of view there are no less than 95°/ showing some 
sort of banding on the under-side, while on the upper-side 
there are only 56°/, and of these only 10°/ that are 
well banded. 
Mechanitis polymnia. 
This species, which in point of numbers comes next 
to Melinwa mneme, is here as elsewhere a very constant 
one. I have estimated that at least 700 specimens have 
passed through my hands and I have detected only one 
‘example that showed any tendency towards a darkening 
of the hind-wing. This individual, a female, was taken on 
March 14th, 1905. On the upper-side the whole of the 
ground colour is darker and in the hind-wing the central 
black band and the black marginal band are considerably 
extended so that at the anal angle and near vein 5 these 
just meet. On the under-side of the hind-wing there is 
an even greater amount of black scaling. The costal 
band is increased in width in addition to the central and 
marginal bands, while the latter join at several points and 
between veins 4 and 5 completely coalesce. 
There is a specimen that shows a very distinct yellow 
apical streak just as in the previous species M. pannifera 
but which is quite normal in the size of the band of the 
hind-wing. It also exhibits an almost complete suppression 
of the black mark between veins 2 and 8 of the fore-wing, 
and this also is a much more common phase of variation 
in the previous species. 
Ceratinia species. 
There yet remain the Ceratinia species, which although 
not very conspicuously within the group nevertheless link 
up certain other species of Napeogenes, Sais and Ceratinia. 
