THE ENTOMOLOGIST 



Vol. XXXV.l MAKCH, 1902. [No. 466. 



FORMATION OF PATTERN ON EGGSHELL OF A SPECIES 

 OF LEPIDOPTERA. 



By Ambrose Quail, F.E.S. 



Messrs. Dawson and Woodhead published * the results of 

 some experiments with certain fats and waxes, showing that on 

 cooling these form into shapes of a "crystalline" nature; melted 

 beeswax forming into natural hexagons, the dimensions of which 

 may be varied by the thickness of the wax, microscopical hexa- 

 gons resulting when very thin. 



Analogy between these naturally formed "crystalline" shapes 

 of fats and waxes, and the sculpturing of the eggshell of lepi- 

 dopterous ova suggests itself, and to this I refer in my paper on 

 "Embryology," Part I. (Trans. N. Z. Institute, vol. xxxiii.). A 

 recent examination which I made will no doubt be of interest, 

 and so far as it goes justifies the analogy. 



The ovum of Melanchra (Mamestra) mutans has very distinct 

 sculpturing, probably not more so than other Mamestra, but the 

 longitudinal ribs are strongly developed, the transverse lines 

 being very fine, it is really only with high magnification it is 

 seen that the fundamental pattern is a modified hexagon ; at 

 the micropylar area the pattern is definitely hexagonal. Theore- 

 tically, it might be suggested that the strong parallel ribs assist 

 the ova to keep in position until deposited, but this does not 

 appear to be so. 



Within the abdomen of Hepiali the ova are connected by 

 thread-like tissue, each ovum forming a definite part of long 

 strings of ova, and are not easily separable. The ova of M. 

 mutans are not so connected by tissue ; in fact, I was unable to 

 detect any such bearing definite relation to the ova, which are 

 smooth, placed end on end, pressed flat against each other, so 



* ' Natural Science,' vol. xv. p. 347. 



ENTOM. — MARCH, 1902. F 



