54 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



and FulgoridaB. The wiugs of the lepidopterous pupa may be said to be in the nymph stage of 

 the ametabolous insects meutioued, since they are direct outgrowths from the tergites of the 

 segments from which they arise. If the wing-cases of any lepidopterous pupa, together with the 

 meso- or metathorax, are, before its hxrval skin is molted, removed and spread out, they bear, as 

 Spuler shows, a striking resemblance to those of a beetle, Termes, Psocus, or any Hemipterous 

 uyiuph. There are no traces in the pupa of any of the isolated ehitinous pieces in the membrane 

 connecting the wings with the trunk, which are seen in the imago. If the wing of the immature 

 imago is removed from the pupal wing case, it will be seen to ditt'er greatly in shape and venation 

 from that of the pupa. The pupal venation is ancestral and phylogenetic; that of the imago is 

 more specialized, showing the results of a long process of adajttation and modification. So it is 

 with the appendages; those of the maxilhe, labium, and of the legs ditt'er greatly, as anyone has 

 observed who has studied fresh pupa;, as compared with those from which the imago is ready to 

 emerge. Those of tlie ])upa show important differences; they are not simply cases, but ditt'er in 

 structure, and possil)ly represent the appendages of an ametabolous ancestor, a i^rogeuitor which 

 may have descended from the campodeiform ancestor of the class of insects. 



The iniportan(!e of the pupa is also seen when we compare those of the genei alized Lepidoptera 

 with the more primitive generalized dipterous families Bibionid;e, Cecidomyiidte, Tipulidae, 

 Mycetophilidfe, etc. The close resemblance between the orthojraphous Dipterous pupa and Tineid 

 I)upa att'ords strong evidence that the two orders are not only closely allied, but even that they 

 may have originated from a common ancestry, the loss of thoracic and of abdominal limbs and the 

 reduction of the head and its appendages of dipterous larvte, as well as the reduction of the 

 hind wings, being due to modification from disuse; In the Dipterous ])ui)a (Culex, etc.) the hind 

 pairs of wings are nearly as well developed as those of lepidopterous pu]>a'. 



8. The imaginal features iu the haustellate Lepidoptera will in general be found to correspond 

 with the pupal characters, though they are not so salient aud striking as the latter after these 

 have been once observed and appreciated. In the moths (Heterocera) especially, tlie adaptative 

 characters have concealed the more fundamental or primitive characters. What we regard as 

 adaptative or secondary characters are the absence of vestiges of mandibles and of maxillary 

 palpi, coupled with the great development of the maxillte themselves, the usually broad frenate 

 wings, and the difterence in shape of the two pairs, besides the specialization of the scales, not 

 only of the wings, but of those forming the vestiture of the legs (iu Noctnida-, etc.). 



9. What we regard as generalized or ancestral characters in the haustellate Lepidoptera are 

 those which have proved of especial service in studying the phylogenj^ of the order. These are 

 the retention of neuro])teroid characters, such as the square head, the small eyes, the vestigial 

 mandibles; in the Eriocephalidae, the retention of the lacinia and galea, the retention of the 

 maxillary palpi; in the higher moths the elongated thorax, the large metathorax, with separate 

 scuta, the exserted large male genital armature of Micropteryx aud of the Psychida?, the small 

 narrow wings of both pairs, and the trichopteriform venation of the more generalized Tineina 

 and of the Eriocephalida' (Protolepidoptera); also as respects the markings of the wings, the 

 absence of highly colored spots, and even of bars crossing the wings. When, as in the highly 

 colored Tineids, the wings are spotted, they are often barred, this style of markings seen in Adela, 

 having been possibly handed down from or at least reminding us of certain beautifully orna- 

 mented and barred trichopterous genera. 



It will be seen, then, as we pass up from the Protolepidoptera to the butterflies, that there 

 has been more or less extinction of neuro])teroid features and an increasing specialization of the 

 parts of the thorax, of the maxillfe, of the shape of the wings, including their scales and markings 

 in general, spots succeeding bands and bars, brighter and more varied markings the dull uniform 

 hues of many micros and Bombyces. 



THE STEM FORMS OR PROGENITORS; OF THE LEPIDOPTERA. 



It seems to us that in the discovery of two-lobed maxillne in Eriocephala, and other anatomical 

 features we have new data for discussing this subject, or at least for critising the view perhaps 

 quite generally held that the Lepidoptera have directly descended from the Trichoptera or from 

 forms more clo-iely resembling them than other neuropteroid orders. 



