12 



Modern Requirements in Oval and Larval Description. 



By J. W. TuTT, F.G.S. 

 {Abstract of Address March loth, 1904.) 



Mr. Tutt referred to the admirable work which was being done 

 by a number of members of the Society in obtaining photographs of 

 the ova, larvie, and pupse of Lepidoptera, but strongly expressed the 

 view that this work, good as it was, did not go far enough for our 

 modern requirements. He desired that those who took the trouble 

 to obtain and photograph these objects should add to them a sum- 

 mary of all the obtainable details as to form, structure, colour, 

 comparison, etc., so that future workers may have a mass of detail 

 upon which to generalise and our science may benefit and progress 

 thereby. Dr. Chapman's papers during the last few years had produced 

 a complete revolution in our ideas concerning these early stages, and 

 his methods of study had given us a mass of detailed information of 

 inestimable influence on all the more modern schemes of classification. 



Broadly speaking, he said that the eggs of all Lepidoptera are 

 divisible into two groups, which are known technically as "upright " 

 and " flat " eggs. Every egg has a tiny little rosette of minute cells, 

 which contains a number of microscopic canals leading into the 

 interior of the egg, and by means of which the fertilisation of the 

 egg is effected. This rosette is the micropyle, and if the egg be laid 

 so that the micropylar axis is vertical to the surface on which it is 

 laid, it is called an " upright " egg, and if laid so that the micropylar 

 axis is horizontal to the surfixce on which it is laid, it is called a "flat" 

 one. Eggs of butterflies are upright eggs, while the greater number 

 of those of moths are flat eggs. It will be found on closer examina- 

 tion, that the upright eggs are, as a rule, eggs with only two axes of 

 measurement, the vertical and the horizontal, the latter being the 

 same in all directions, a horizontal section being circular. In the 

 flat egg there are three different measurements, length, width and 

 height, the two horizontal axes being of different lengths, and the 

 horizontal section roughly elliptical in outline. 



Upright eggs are generally ribbed vertically, hemispherical or rather 

 more than a hemisphere, showing very fine sculpture and with the 

 micropyle at the top. Flat eggs are generally comparatively smooth, 

 with scarcely any or no trace of markings or reticulations and with 

 the micropyle at the end. Besides the above characters, notes should 

 be made of the sculpture of the shell, the more or less transparency, 

 the character and completeness or incompleteness of the ribbing, the 

 colour and its changes at different ages of the eggs, and the smooth- 

 ness or roughness, dulness or glossiness, of the surface. 



Attention should also be given to the general habit of the egg- 



