T. BtStORTATA (cUEPUSCULARIa) AND T. CHEPUSCULAIUA (bIUNDULARIa). 287 



shake the position taken up by those lepidopterists who have studied 

 the insects in all their stages. Juggling with a few captured 

 specimens on the " white" and " brown," and " March " and " June " 

 lines will not do it. 



(T« be CDiitinucd). 



The characters of the eggs of Lepidoptera, as affording a basis 

 for classification. 



Uy T. A. CHAPMAN, M.D., F.E.S. 



The strong tendency of all eggs is, no doubt, to be spherical, a 

 tendency that is as obvious in the highest as the lowest groups of 

 animals. It is not, therefore, surprising that this form of egg is very 

 common, or, at least, a near approach to it is common, in the Lepi- 

 doptera, and it is, perhaps, no proof that they are lower forms that 

 this is the shape of the eggs of the EKiocEPHALiDFri and HEPiALiDtis, 

 and that in the Mickopteryuides it is only so far modified as to be, in 

 many cases, somewhat flat-shaped, by a slight lengthening and 

 narrowing towards the micropylar pole. 



In nearly all groups, however, in Avhich the egg is laid on some- 

 thing (a leaf, or what not), it is more or less flattened on the attached side. 

 When we come to examine the nature and extent of this flattening, and 

 its relation to the form of the egg generally, we find it possible to 

 place eggs under one or other of two large classes, one, in which the 

 flattened side is at the antipodes of the micropyle, and which we may 

 regard as being placed in an upright or vertical position on its 

 proper or natural base. The other lies, so to speak, on its side, so that 

 the micropyle is at one end, the proper base at the other, both equally 

 removed either from the upper surface or the attached face. 



Though I have suggested the nadir of the micropyle as the proper 

 base of the egg, this idea is really quite conventional, and there is 

 some reason even to suppose that it is erroneous, since the upright or 

 vertical egg is possibly derived from the flat or lateral form, whilst 

 there is little ground to believe the lateral is ever derived from the 

 vertical form. 



When we enquire what species or families of lepidoptera possess 

 these two difterent types of eggs we are met at once with facts that 

 shoAV that the distinction is one of importance. Amongst the Inco3iplet.k 

 (Micros) we find a great preponderance of forms with flat eggs, but our 

 knowledge of the ova of these is so imperfect that it is safer to pass 

 them by, not, however, without a suspicion that amongst them a 

 variation from a flat to a vertical egg is not uncommon. But amongst 

 the higher forms, or Obtecta; (Macros) we find in each family that the 

 whole of the family adheres throughout to one form of egg. 



We find, further, that those families, which have been for various 

 reasons associated together in our more recent classifications, agree in 

 the type of egg, and it seems highly probable that a classification that 

 so places any particular family is more correct as regards that family 

 than is one that places it otherwise ; for instanfte, Mr. Dyar associates 

 the Notodonts Avith the Noctuid group, and since both have vertical 

 eggs, he is more probably correct than Mr. Meyrick, who places them 

 amongst groups with flat eggs. 



If Ave consider first the vertical eggs, we find them in IJutterflies, 



