131 



escape from a lower and more embryonic physical condition, Ave 

 may consider it as a reminiscent action, marking the successive 

 developmental halts in the kingdom, through which it is given to 

 some to pass, and at which it is fated that others shall perish. 



Within the two series of suborders of Hesapoda, a synthetic t^^pe 

 has been shown by Packard to exist in the ISTeuroptera. In compar- 

 ing the Lepidoptera, a synthesis may be detected in the Bombycidae. 

 Thus the Lithosiinae resemble the Pyralidae, the Arctiinae the Noc- 

 tuidae, the Attacinae the Geometridae ; lower down the Cossinae the 

 Tineidae, though the actual interchange of the two latter must be 

 doubted, even since the discovery of such a form as Morpheis, per- 

 liaps the most extraordinary form of the suborder. Professor Pack- 

 ard has compared the thoracic structure of Sthenopis with the 

 Neuropterous Polystichoetes. And, in a general comparison Avith 

 the Neuroptera, the Lepidoptera are seen to advance along a line of 

 parallel development. Indeed the development of all the suborders 

 is at least biserial, reflecting the progress of the Order. Thus the 

 Diurnals resemble the higher Neuroptera in the position of the wings, 

 while in the lower Neuroptera these are deflexed as in the Moths. In 

 considering the general progression of the Hexapoda, the Devonian 

 and earliest forms known seem to be Neuropterous, nor is there yet 

 sufiicient evidence to prove that the common origin of Hexapoda 

 is to be carried back through suborders exclusively fossil. Yet that 

 the position of the N'europtera suggests such a third series, Avhich 

 is now no longer living, and Avhich has given rise to the Orthoptera, 

 Hemiptera and Coleoptera, and again to the Diptera, Lepidoptera 

 and Hymenoptera, cannot be denied. And that the Lepidoptera 

 are the more recent, palaeontological evidence rather confirms, 

 while we should not expect the Butterflies to be largely repre- 

 sented among the flowerless forests of the Carboniferous period. 

 On general grounds we shall agree that the common origin of Tra- 

 cheata is to be sought in the Zoeaeform Crustacea as suggested by 

 Haeckel. Packard's objection, that Leptus begins life on a higher 

 level than JSTauplius can hardly lead us to reject the crustacean origin 

 of Hexapoda, a type which must have been evolved from a littoral 

 biregional ancestry. In studying the larval forms of Hexaj)6da we 

 follow Packard's exposition of larval types. The exceptional i^osi- 

 tion of tiie abdomen in the young Lachnosterna recalls the usual 



