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Annals Entomological Society of America [Vol. XV, 



A brief account of a typical instance of hatching follows: 

 The embryo began a series of movements calculated to pull the 

 tip of the abdomen towards the posterior pole of the egg. 

 This region became crowded and the embryo pushed upwards 

 and outwards slowly. The upward movement was rather 

 quick and with some effort, while the downward one appeared 

 to be a slipping back to its previous position. Along with these 

 movements, there was some outward pressure brought to bear 



Fig. 4. An egg mass of Chaidiodes pectinicornis hatching. 

 (Photo by H. S. Barber, 1912). 



on the head region which culminated in the penetration of the 

 chorion by the upper lobe of the burster. It was later observed 

 that it is frequently difficult to ascertain if it has cut through 

 the chorion or whether it is merely closely appressed. In this 

 case, two whitish triangular areas appeared on each side of 

 the burster, their bases next to it. The writer interpreted these 

 as air bubbles beneath the chorion, the edges of which had 

 been raised up in the cutting process. As the embryo con- 

 tinued the upward pressure, the burster was pushed through 



