36 FOSSIL BUTTERFLIES. 



the same in the two, but the costal nervure appears to be much shorter in 

 Lethites. 



With Lethe (PI. II, fig. 6) and Debis (PI. II. fig. 10) the fossil genus can 

 better be compared, as far as the form of the wing, the dilated costal vein, and 

 the position and direction of the straight vein closing the cell are concerned; 

 but in both these genera only a single superior subcostal nervule is emitted 

 before the apex of the cell; the form of the cell again shows rather closer 

 affinity between Lethites and these genera, although the difference in these res- 

 pects is but slight. It is by no means distantly related to Enodia, in which 

 two subcostal nervules are emitted before the tip of the cell, but differs from 

 it in the much greater and more abrupt swelling of the costal vein, and in the 

 much greater distance beyond the second divarication of the median nervure at 

 which the vein closing the cell meets this nervure. It even exhibits no small affin- 

 ity to Cercyonis, and especially to those species in which there is little dilation 

 of the median nervure; the costal nervure is swollen in precisely the same 

 way, and the superior nervules of the subcostal nervure are much the same ; but 

 the form of the wing is strikingly different, and the lowest subcostal interspace 

 much wider at the base, in comparison with the width of the base of the sub- 

 costo-median interspace, in Cercyonis than in Lethites; and this seems to be a 

 character of considerable importance. It may be noted in this connection that 

 the markings of the fossil must have closely resembled Cercyonis Pegala. 



Its nearest ally among living European types would seem to be Maniola 

 Hermione, in which the costal and median veins are about equally swollen. The 

 neuration of Lethites agrees with this genus in much the same way as it does 

 with Cercyonis, the comparative width of the interspaces beyond the cell being 

 very different in the living genera from what it is in the fossil. In the form 

 of the wing Maniola agrees much better with Lethites than Cercyonis does, but 

 the costa is much more arched, and the cell is much the longer in Maniola; were 

 there no obscure spot in the lower median interspace in the male of M. Hermione, 

 the markings of the fossil would agree with it almost perfectly. 



