252 ANCESTRY AND CLASSIFICATION. 



But perhaps the most striking point of affinity 

 between these two groups lies in the possession, 

 on the front tibiae, of the same characteristic foli- 

 ate appendage [see Fig. 173], which is wanting in 

 all other butterflies ; this, like the possession in 

 the skippers of two pair of spines on the hind 

 tibiae is certainly a mark of degradation, by which 

 they are allied to the lower families of Lepidop- 

 tera. We find therefore that in the very peculi- 

 arities of their structure wherein they depart from 

 the higher butterflies, they are most closely re- 

 lated to the skippers. 



But, again, the swallow-tails are universally 

 conceded to be so closely allied to the white and 

 yellow butterflies that they are invariably placed 

 next them. Consequently, if the swallow-tails 

 are placed highest in the scale, the yellows must 

 go with them ; nobody questions this ; yet the 

 yellows possess not a single one of the character- 

 istics by which a high rank is claimed for the 

 swallow-tails ; commentary upon this is needless. 



Having thus in a general way attempted to ex- 

 hibit by the diagram the relationship and relative 

 perfection of the different types, reducing them 

 primarily to four larger groups, we may, through 

 several features in their structure and habits, 

 prove the general correctness of our estimate, by 

 tracing a regular progression in passing from the 

 lower to the higher butterflies. These features 



