THE EGG AND EGGLAYING OF OURAPTERYX SAMBUCARIA. 



201 



just clear of where the latter touched the sheet of paper on which it 

 stood, and the number has been added to since until today (July 12th), 

 when there are apparently about 300 eggs. 



They are laid chiefly in little batches of from 5 to 25 apiece, some, 

 however, singly. The remarkable point about the eggs, however, is 

 that they are highly specialised upright eggs, the micropylar axis being 

 quite perpendicular to the surface on which they are deposited. They 

 are bright yellow m colour, and might, so far as their general appear- 

 ance is concerned, be Satyrid or Nymphahd eggs, benig circular in 

 transverse and broadly oval in longitudinal section, the base wider than 

 the apex, pale yellow in colour, indeed, not greatly unlike the tint of 

 the imaginal scales. The egg is distinctly ribbed from the base to the 

 micropylar area, with about 16 longitudinal keels, the edge of each 

 keel looking somewhat smooth and shining, with a noticeable irides- 

 cence under a low power (hand-lens) ; between these are a number of 

 transverse lineations surrounding the egg, so that the Avhole of the ovum 

 has a peculiar butterfly-egg aspect. 



All the eggs appear to be laid in this position except one ; this one 

 is the only one that is off the glass, and is on the paper on which the 

 glass stood, i.e., all are laid as upright eggs on a vertical surface, 

 and the odd one is laid as a flat egg on a horizontal surface. This, 

 laid on its side, has, as it were, the base of the egg higher than the 

 apex, owing to its being thicker at that end. The egg is apparently 

 quite unsuited for being laid in this position. 



The Geometrid egg that most resembles this in its manner of being 

 laid is that of Dasi/dia obfascata. Yet the supposed allied Gnophids have 

 most normally-shaped flat eggs, which differ, not only in position, but 

 in shape, method and style of ornamentation, and, structure to such 

 an extent that one wonders what so great a difterence indicates. 



Then there are some of the Acidaliids that lay upright eggs, but 

 here we And a good deal of transition, some ? s laying, in confinement 

 at least, a fair percentage of eggs in flat and in upright position, and, 

 besides, the structure of these upright laid eggs is less distinctive, and 

 appears much rather that of a flat egg on end than a bona-fide upright 

 egg of circular transverse section. The eggs of Dasi/dia obfascata and 

 Ourapteryx, aambucaria, which are very unlike, and which two insects 

 have no real close alliance, appear to have developed per saltuin as 

 highly specialised eggs of a type common in the Noctuo-Papilionid 

 stirps, but very rare outside it. 



There are, I suspect, other genuine upright eggs among the 

 Geometrids. These ought to be carefully studied. The evolution of 

 the Coleophorid egg in its generalised and specialised forms, although 

 already noted, still demands attention. Dr. Chapman has shown us 

 special evolutive directions in which eggs of other so-called "micro " 

 groups have upright eggs. Still there are so many men who collect 

 and rear " Geometrids," compared with those who rear the "micros," 

 that one might reasonably expect additional knowledge on all points 

 relating to the biology of the Geometrids. 



On the morning of July 28rd the ? died. She had laid 547 eggs. 

 The earliest laid eggs were now of a very deep orange colour, through 

 which they had passed by a series of different shades of orange from 

 their first yellow tint. Only 28 eggs altogether were laid on the paper 

 on which the glass under which the 2 was confined, and of these 



