342 LEPIDOPTERA CHAP. 



3. The front legs are like the other pairs ; their tibiae however 



pads ; the claws are large, not bifid, and there is no empodium ; 

 the inetanotum is completely exposed at the base of the abdomen, 



Fain. PAPILIOXIDAE. 



4. The front legs are like the other pairs ; their tibiae however possess 



pads ; the claws are small, toothed at the base, and there is an 

 empodium ; the metanotum is concealed by the prolonged and 

 overhanging mesonotum. Fain. HESPERIIDAE. 



The relations between the families Eiycinidae, Lycaenidae, 

 and Nymphalidae are very intimate. All these have the front 

 legs more or less modified, and the distinctions between the 

 families depend almost entirely on generalisations as to these 

 modifications. These facts have led Scudder to associate the 

 Lycaenidae and Erycinidae in one group, which he terms 

 " Rurales." It is however difficult to go so far and no farther ; 

 for the relations between both divisions of Rurales and the 

 Nymphalidae are considerable. We shall subsequently find that 

 the genus Libythea is by many retained as a separate family, 

 chiefly because it is difficult to decide whether it should be 

 placed in Erycinidae or in Nymphalidae. Hence it is difficult to 

 see in this enormous complex of seven or eight thousand species 

 more than a single great Nymphalo-Lycaenid alliance. The 

 forms really cognate in the three families are however so few, 

 and the number of species in the whole is so very large, that it 

 is a matter of great convenience in practice to keep the three 

 families apart. It is sufficient for larger purposes to bear in 

 mind their intimate connexions. 



The Papilionidae and Pieridae are treated by many as two 

 sub-divisions of one group. But we have not been able to find 

 any justification for this in the existence of forms with connect- 

 ing characters. Indeed it would, from this point of view, 

 appear that the Pieridae are more closely connected with the 

 Lycaenidae and Erycinidae than they are with Papilionidae ; 

 in one important character, the absence of the pad of the front 

 tibia, the Nymphalo-Lycaenids and the Pierids agree. It has 

 also been frequently suggested that the Papilionidae (in the 

 larger sense just mentioned) might be associated with the 

 Hesperiidae. But no satisfactory links have been brought to 

 light ; and if one of the more lowly Hesperiids, such as Thanaos, 

 be compared with one of the lower Papilionidae, such as 

 Parnassius, very little approximation can be perceived. 



