Proceedixgs, 1915. 109 



Evolution of the Lepidoptera from a Pupal and Oval Standpoint.' In 

 this we had a factor which could be applied in the way desired, and that 

 showed us, not which were specialized and w'hich generalized super- 

 families, but which of the specialized and which generalized superfamilies 

 of the various stirpes were related to each other. This paper showed 

 that the form of egg found in each different superfamily is very constant, 

 and that there appears to be no rapid transition from one form to the 

 other among the Lepidoptera. There are, broadly, among the higher 

 Obtect families two forms of egg. the flat and the upright egg. the former 

 being divisible into the Geometrid and the Bombycid. The Geometrid 

 egg is generally marked by a greater roughness and by coarser ribbing 

 or network ; the Bombycid is smoother and more polished, although there 

 are many striking exceptions to this otherwise pretty general rule. 



" Chapman is inclined to derive these two forms of flat eggs, from 

 distinct origins, very low down in the evolutionary scale, but thinks it 

 probable that the various forms of the upright egg (Noctuid, Papilionid, 

 etc.) had a common origin, though very low down. He is supported 

 in this conclusion by the presence of the chin-gland, which is found 

 only in Papilionids, Noctuids, Notodonts, and other superfamilies with 

 upright eggs, but nowhere among those with flat eggs, and we may 

 accept Chapman's conclusion that, however widely the butterflies are 

 separated from the Noctuids (and the evidence of the Hesperid pupa 

 shows that the butterfly stirps separated from the Noctuid stirps a very 

 considerable way below any Noctua-like form usually placed with the 

 Macros), the evidence of the egg and the presence of the larval chin- 

 gland sufifice to show that they jointly separated from the Geometrids 

 and Bombycids still lower down. The evidence of the egg, too, shows 

 that the Noctuids and Papilionids were not derived, as Meyrick suggests, 

 from any Pyralid form, as the Pyralids are, in some respects, of a higher 

 t3'pe than the Hesperids, and yet the former still belong very markedly 

 to one of the flat-egged stirpes. No very clear indication has yet been 

 obtained to show where the upright egg branched from the flat egg. 

 The most probable point is between the Cossids and the Zeuzerids. 

 These superfamilies are, in many respects, somewhat closely allied. 

 The former has an upright, the latter a flat, egg, and Chapman considers 

 that we have here, probably, the point where the two forms are still 

 unfixed and capable of easy variation. The alliance (by pupa) of Castnia 

 with Cossus would perhaps point to this also as being somewhat near 

 the origin of butterfly stirps. 



" Accepting the principles here laid down, there can be no doubt that 

 the flat egg is the ancestral form, and the upright egg a more specialized 

 structure. Examination of a large number of eggs of species belonging 

 ti) several superfamilies shows that the upright eggs which characterize 

 the Notodonts, Noctuids, Lithosiids, Euchromiids, Lymantriids, and 

 Papilionids are modifications of one and the same structure." 



