40 NEW-WORLD MIMICS [ch. 



In connection with it there is a feature of peculiar 

 interest in that the transparent effect is not always 

 produced in the same way. In the Ithomiines such 

 as Thyridia, where there are normally two kinds of 

 scales, the wider ones for the most part lose their 

 pigment, hecome much reduced in size and take on 

 the shape of a stumpy V (PL XIV, fig. 3). Also they 

 stand out for the most part more or less at right angles 

 to the wing 1 , and the neck by which they are joined 

 to the wing membrane is very short. The longer 

 and narrow form of scales also tend to lose their 

 pigment and become reduced to fine hairs. In Dis- 

 morphia the scales, which are of one sort, are also 

 reduced in size though apparently not in number. 

 Like the wider scales of the Thyridia they tend some- 

 times to project at right angles to the wing membrane, 

 though not to the same extent as in the Ithomiine : 

 possibly because the neck of the scale is nob so 

 short. As in Thyridia these reduced scales lose 

 their pigment except in the transition region round 

 the borders of the transparent patches. In Ituna 

 there is a difference. The scales are not reduced to 

 the same extent in point of size. Their necks are 

 longer as in normal scales and they he flat on the 

 wing membrane. The majority of the scales, as in 

 the preceding cases, lose their pigment, but mixed 

 up with them is a certain proportion, about one-quarter, 



1 These descriptions are taken from preserved specimens which 

 I owe for the most part to the kindness of Dr Jordan. I have not 

 had an opportunity of examining fresh ones. 



