Quail. — On New Zealand Lepidoptera. 159 



Art. XV. — Embryological Structure of Neiv Zealand Lepid- 



optera : Part I. 



By Ambrose Quail, F.E.S. 



[Read before the Wellington Philosophical Society, 12th March, 1901.] 



Plate IX. 



The subject has of recent years received the attention of 

 capable authors in England and America, and some notes on 

 the embryology of Lepidoptera of general interest, if applied 

 to local species, may be of use to New Zealand students in 

 directing attention to its scientific importance. 



The number of eggs laid by Lepidoptera varies inversely in 

 proportion to specialisation. Assuming primitive productivity 

 to be great, Hepialida — an ancient group — deposit their ova 

 indiscriminately at random amongst the herbage in great 

 quantity, probably thousands in some genera. The develop- 

 ment of ornamentation of the ovum, the degree of develop- 

 ment attained within the ovum by the ensuing larva, may 

 cause greater assimilation of egg-producing matter per ovum, 

 hence a reduction in the number of ova laid per species. 



It is characteristic of Arctidce, Noctuce, Gcometrce to attach 

 ova in batches to branch, twig, leaf, or what not, and, gene- 

 rally speaking, in these groups the number of ova is limited, 

 in some species to a hundred or so. Among Bhopalocera, the 

 position is usually selected and ova deposited singly, and the 

 number deposited is small. 



Individual species in any group may be noted to have a 

 greater productivity than is usual, but some female Lepidoptera 

 develope a greater capacity for egg-production at the expense 

 of imaginal structures ; thus reduction may be counteracted 

 and rate of productivity maintained. Apterous female Orgyia, 

 Hybernia, &c, are extreme examples of such. 



Ova of Hepialida (Porina and Charagia) are smooth and of 

 spherical shape. This may not indicate generalisation, since 

 Psychidce (GUceticus) ova, though smooth, are, longer than 

 broad, and have equal claim to be considered a primitive egg- 

 shape ; there is little doubt, however, that the smooth egg 

 is more primitive than the sculptured egg. Eggs of certain 

 groups are laid on the side (lateral) ; among these a Tineid 

 egg (fig. 3), with obscure sculpture, is a more ancient type than 

 such lateral eggs as have parallel ribs, and are also probably 

 more primitive than Geometrid eggs, with distinct hexagonal 

 sculpture — Selidosema, Asaphodes (fig. 4). Eggs of certain 

 groups are attached on end (vertical) ; among these the 



