xii
Introduction.
| b1. | Front pair of legs perfect in both sexes. |
| a2. | Vein 1 a in hind wing wanting; claws simple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
Papilionidæ. |
| b2. | Vein 1 a in hind wing present; claws bifid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
Pieridæ. |
| b. | Precostal nervure in hind wing absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
Lycænidæ. |
| B. | Antennæ wide apart at base; hind tibiæ generally with a medial as well as a terminal pair of spurs; all the veins in the fore wing from base or from cell, none forked or coincident beyond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
Hesperiidæ. |
Opinions vary as to the probable line of descent of the butterflies. Packard considers that the moths of the family Castniidæ are their predecessors; Meyrick traces their descent from the Thyrididæ group Pyralidina of the Frenatæ, Hampson from the Zyrgænidæ.
However this may be, a provisional genetic tree for the butterflies can be constructed as below.
_-_p._xii.png)
The evidence of one family group of the butterflies being derived from another is entirely inconclusive. Specialization of forms has followed often parallel lines in all the families, but similar specialization, when it occurs in different groups, is no proof of genetic descent, but of independent development along similar lines.
The tendency in modern Systematic Natural History is to
