92 



FOSSIL BUTTERFLIES, 



rig.q. 



I'alaeontina oolitica Ball. 

 Facsimile of Butler's second sketch. 



found it impossible to make a tracing of it, and therefore drew the whole by meas- 

 urement This sketch is now produced on PI. XIX, fig. 4 [see fig. 6] ; and any 



body can judge for himself whether or 

 not it is more perfect than that which I 

 previously figured (see Geol. Mag., 1873, 

 Vol. X, p. 2, PI. I, fig. 2 [see fig. 5] )." 



"In order to show the extent to which 

 the Jermyn street example is deficient, I 

 have restored it (fig. 5 [our fig. 7]), filling 

 in the blanks fi'om Mr. Charlesworth's 

 specimens. By comparing the latter with 

 the wing of Dasyophthalma (fig. 1), and 

 Cicada (fig. 2), one may come to a pretty 

 accurate conclusion as to the group of insects to which it ought to be referred."' 



The neuration of Lepidoptera as a group is the simplest in the whole order of 

 insects, if we except that of the elytra of Coleoptera; this is due, doubtless, to the 

 fact that their wings are heavily scaled, con- 

 cealing the nervures; just as in Coleoptera, 

 the thickness and opacity of the fore wings 

 often completely masks the neuration. 



The normal number of veins in the 

 wings of insects is six, disposed to a cer- 

 tain extent in pairs; the middle pair usually 

 ramify to a greater extent than the others, and support most of the membrane of 

 the wing. In butterflies the foremost vein is always absent and very commonly 

 the hindmost, so that there are but five (often but four) principal veins, usually 

 designated, though not very appropriately: costal, subcostal, median, submedian 

 and (when present) internal, reciting them in their order from in front back- 

 ward. The costal, submedian and internal nervures are invariably simple and 

 terminate at the margin, or are occasionally lost in the membrane of the wing. 

 The subcostal and median nervures, on the other hand, are as invariably forked, 



> Geo). Ha«. [2] 1, 448. 



Fig. 7. 



Palaeontiiia oolitica Butl. 



The neuration, after Butler's second sketcli. 



