Contribution to the life history of Orina tristis. 247 



When the egg-sliell is split, a portion of the larva slightly 

 protrudes through each slit, but the larva soon manages 

 to turn round and escape through one of them head first. 

 Since the larva can emerge through only one of them, 

 why should there be two slits ? These do not reach the 

 top of the shell and are still further from reaching the 

 bottom, but now and then they deviate from this symmetrical 

 arrangement, one may be longer than the other, and this 

 deviation may account for one slit only existing and that 

 one reaching to the top of the egg-shell. This is com- 

 paratively rare, but still not infrequent, and was the only 

 form I noticed in the few eggs I had in 1900. The two 

 slits are probably useful in affording the larva escape by 

 one, when the other is obstructed by the egg being 

 against one of its neighbours, or possibly even glued to 

 it or some other object, by some accident, either in the 

 disposal of the parental glue that fastens the egg to the 

 surface on which it is laid, or by a neighbouring egg 

 being injured and its contents acting as a cement, as 

 must not infrequently happen to eggs laid naturally on 

 a leaf. The eggs are laid in regular order, in several 

 adjacent rows, and are slightly inclined to the surface of 

 attachment, instead of being perpendicular to it, so that 

 one side of the egg is tolerably free, the other almost or 

 even actually touches its neighbours. The larva could 

 hardly hope to escape, if a solitary slit occurred on this 

 side. I had made many observations of these beetles, of 

 their egg-laying, of their hatching, had fed many of them 

 from hatching to full-fed larv^, and was still of the opinion 

 that this species could not be 0. tristis, because I had 

 observed 0. tristis lay eggs quite ready to hatch, whilst 

 my insects from Pino laid eggs quite undeveloped. I was, 

 however, puzzled to find that some eggs hatched in a few 

 days whilst others did not do so for over a week. Some 

 showed the imaginal jaws through the shell very early 

 and so on. Still all the eggs I examined when new laid 

 showed no coloured indications of the young larva. 



On August 29th, however, a new experience awaited 

 me. I found several eggs that had been laid since the 

 26th were already hatched. I determined therefore to more 

 closely scrutinise the periods from laying to hatching of 

 future eggs. Further light was closer at hand than I had 

 expected. At 11 a.m., August 29th, the beetles were fed 

 and as usual placed in a clean jar with fresh food, clean paper, 



