1889.] MR. A. G BUTLER ON A NEW FOSSIL MOTH. 293 



In the list of Insect-remains determined by the late Mr. Frederick 

 Smith of the Zoological Department, two Lepidopterous insects, re- 

 ferred to a species of Lithosia, are recorded. 



The fossil now to be described is especially interesting on account 

 of its unusually perfect condition, which not only enables one to 

 trace without difficulty the main features of its structure, but gives 

 a very good idea of its pattern and colouring when living. 



A study both of fossil and recent Lepidoptera leads one to the 

 conclusion that the Butterflies and Moths of the past were by no 

 means so highly coloured as those of th^ present day ; that in the 

 earlier ages of the world the large family Nymphalidse was repre- 

 sented by brown and black species, the Pierinse by species wholly 

 white, or white bordered with black ; the Hesperiidfe and most, if 

 not all, of the Moths by brown, black, and white forms. Even at 

 the present day these three tyj)es of colouring are far in excess of 

 more brilliant hues, and the fact of dull coloration being, as a rule, 

 more abundantly found in female than male Lepidoptera, even in the 

 more brightly coloured genera, tends to prove that sexual selection 

 has been the principal agent in beautifying the species now existing. 



The Lepidopteron found by Mr. A'Court Smith belongs to the 

 Euschemidse, a family of Geometrid Moths allied to the Zerenidse 

 (popularly called Magpie moths) and containing some of the most 

 brilliantly coloured of all known Heterocerous Lepidoptera ; it, 

 however, does not belong to the brilliant section of the family, but 

 to a small group of genera for the most part black and white to the 

 present day, though some of them have acquired yellow markings. 



Assuming that the Euschemidse originally consisted of black and 

 white insects, yellow would naturally be the first departure, on 

 account of its being contained in the largest proportion in white' ; 

 and it would follow that in this family yellow markings would be 

 most likely to preponderate at the present time, as, in fact, they do, 

 whilst the black portions of the wing when modified show a violet 

 or, in the more highly specialized forms, a bright blue shot tint. 



Mr. A'Court Smith's discovery belongs to a group of three or 

 four genera which to this day retain their original neutral tints of 

 black and white, and which therefore are in all probability the oldest 

 existing representatives of the family Euschemidse ; these genera are 

 Calospila, Simena, Mniocera, and Craspedosis ; other genera pro- 

 bably remain to be discovered. 



It is a significant fact, as evidencing the permanence of Lepido- 

 pterous forms, that, although at the present time we have numerous 

 brilliantly coloured species and even genera, the primitive forms still 

 have their representatives in nearly allied genera, the colours of which 

 remain dull and the patterns but little modified. This is most easily 

 seen in the best preserved and more recent fossils, such as Neorinopis 

 represented by the black and white Neorina, Mylothrites by the brown 

 forms of Precis, the so-called Pontia freyeri by the females of the 

 S.-American P. suasa, and Thanaites by Thanaos ; the affinities of 



1 White light contains a proportion of about jV yellow. 

 Proc. ZooL. Soc— 1889, No. XX. 20 



