122 CATOOALA PROMISSA. 



cage, to which they adhered ; they were of two differ- 

 ent colours, and I contented myself with choosing 

 three of each, and returning the remainder to Mr. 

 Ross, from whom I afterwards heard they all proved 

 sterile. 



The egg of Catocala promissa is of a good size, of a 

 rather flattened spherical figure, a little depressed in 

 the upper centre and much more beneath, the shell 

 covered with coarse, projecting, sinuated ribs, varying 

 from fourteen to eighteen in number, so close together 

 as almost to hide the surface between them, the de- 

 pressed spot in the centre of the top coarsely reticu- 

 lated ; when fertile it is of a dull drab colour, and so 

 continues through the winter, but, as I found, when 

 sterile it is dark brown, and eventually shrivels up. 



About the middle of April, 1876, while looking at 

 the three drab-coloured eggs, I fancied two of them 

 seemed rather more plump than before, and a close 

 examination proved this to be the case, as a little of 

 the smooth shell had become visible between the rough 

 ribs, and the upper central hollow nearly filled up ; 

 this last on the 18th was completely rounded over, 

 and the ribs were turning paler ; on the 20th they had 

 become whitish, and the interstices greenish-drab 

 colour ; and on the morning of the 21st I found one 

 larva was hatched ; the dull, whitish, empty shell 

 showed a large hole in the side, through which the 

 larva had escaped ; the next morning I saw a second 

 had hatched. At this time none of the oak buds had 

 burst, nor were many much swollen, but I picked open 

 two or three at a time of the best to be found for the 

 young larvaB to feed on, Mr. Ross also, at this 

 juncture, kindly supplying me with a few tender oak 

 leaves which he had contrived to force out; but in 

 placing this food in the cage I noticed one of the 

 larvss, when put on the leaves, swing away from them 

 by a thread, and though I replaced it before shutting 

 the cage, yet it must have again swung out, for at that 

 moment I unconsciously lost it ; however, next morn- 



