ORDER LEPIDOPTERA 59 



interesting and varied assortment of forms in the leaf -feeding 

 Lepidoptera. Of these perhaps the pupae of the Erio- 

 craniidae are the most surprising. In Eriocrania the pupal 

 skin is soft and the various parts are hardly fused together at 

 all. In emergence the head is free to move, the face is lifted 

 up, the jaws (curiously developed and functional structures 

 here, see p. 76) open to pass each other. 



In other pupae there are varying degrees of fusion. Some 

 are nearly as free as these Eriocranids, and some are com- 

 pletely fused and quiescent. Among leaf -mining Lepi- 

 doptera we find these two extremes and most of the inter- 

 vening forms. Thus in Nepticulae, which are primitive, the 

 first six abdominal segments are all free. In Incurvaria the 

 first of these is fixed and soldered with the thorax and so are 

 the first two of them in Tischeria. In Bucculatrix the first 

 two are fixed and the third is nearly so. In the mass of 

 species of the Microlepidoptera the first three of these seg- 

 ments are fixed. In the Gracilariidae the first four ab- 

 dominal segments are fixed but the fifth and sixth (and 

 seventh in the males) are free. Between these and the 

 entirely quiescent pupae, transition forms are lacking save 

 that in the Lyonetidae the parts of the immovable pupa are 

 more feebly fused than in the typical "obtect" pupae, and in 

 some Gelechiids only dorso-ventral movements are possible. 



In the Gracilarids and all the forms having a lesser degree 

 of fusion than these, the pupae are more or less active and 

 twist about when they are disturbed in any way. As in 

 Eriocrania the pupal skin is worked out of the pupal case 

 before the adult emerges. This is accomplished by the 

 movements within the pupal case of the fully-formed adult 

 abetted by ingenious modifications of the pupal case itself. 

 In Lithocolletis and others the top of the head, which is 

 sharpened almost to a beak and often supplied with a 

 toothed crest, makes an excellent ramming tool, while on 

 the dorsal sclerites of the abdomen are patches of small stout 



