THE ANCESTRY OF BUTTERFLIES. 239 



hairs, great length of tongue, and the presence of a middle pair of spurs on 

 the front and usually on the hind legs, in the former developed as a 

 curious foliate membrane ; their eggs are broadly truncate spheres, some- 

 times ribbed ; their caterpillars have a large head with a very thick skull 

 and a very contracted neck, formed of the first body segment and bearing 

 a corneous shield above ; their chrysalids are smooth and uniform, like the 

 })upae of most moths, but in rare instances are pointed in front. In 

 nearly all these features they resemble the picture we drew of the primeval 

 type ; but in the hooked antennae, foliate appendage of the fore tibiae and 

 sexual diversity of the butterfly, the frequently ribbed eggs, the constric- 

 tion of the neck of the caterpillar, and in the occasional projection of the 

 head of the chrysalis, and possibly in the shrouds by which it is supported, 

 they have departed from that type, and most of these peculiarities they 

 share with no other butterflies. The other families appear to have 

 diverged simultaneously from each other shortly after their common sepa- 

 ration from the skippers ; for they contain many characters in common 

 Avhich distinguish them from the skippers, such as the position 

 of the tongue, which is inserted so low down as to give the head 

 a vertical rather than, as in the skippers, a horizontal cast ; the antennae 

 are inserted near together ; the tip of the club is never produced to a dis- 

 tinct point ; the eyes have no distinct overhanging pencil of erect bristles ; 

 and the hinder portion of the ocellar globe is covered with scales, limiting the 

 field of vision. All these, characters probably gained by the higher butterfly 

 stock after its separation from the skippers, are points of minor importance 

 and indicate but a brief period of common existence. Similarly it would 

 appear as if the present families of Lycaenidae and Papilionidae remained 

 together after their common separation from the Nymphalidae, for they 

 contain several important characters in common, particularly the usually 

 small head of the larva and its relation to the first thoracic segment (least 

 noticeable but not lost in the Pierinae), together with the peculiar mode 

 of suspension of the chrysalids. But all three of the higher families must 

 soon have become differentiated and shown each in its own way the char- 

 acters which are peculiar to it. Thus in the imago of the Papilionidae, 

 the metathorax is markedly separated from the mesothorax, the front of the 

 head between the eyes is as broad as high, the eyes themselves are prom- 

 inent and are not infringed upon by the antennal sockets ; while the 

 more special characteristics of the two great groups into which this fimiUy 

 is divided show that it became disintegrated at an early time, though it 

 still retains very striking marks of its close affinity to the lowest types. 

 The diminutive size of the Lycaenidae, the narrowness of the front of the 

 head, the flatness of the eyes, the encroachment of the antennae upon their 

 upper margin, and the consolidation of the metathorax with the mesothorax, 

 together with the tiarate character of the egg, the more or less onisciform 

 structure of the caterpillar, and the rounded, short and compact form of the 



