group of Butter files, 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 polyrtinia. 



This species, which in point of numbers comes next 

 to Melinma 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 specimea that shows a very distinct yellow 

 apical streak just as in the previous species M. pannifcra 

 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 3 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. 



