1920] 



Smith: Hatching in Corydalis 



Heymons (1906) states that the egg burster of the Penta- 

 tomidae is a thickening and speciahzation of the embryonic 

 cuticula. This cuticula is a very thin deHcate structure undoubt- 

 edly rudimentary. It is molted at hatching and with it goes 

 the egg burster. The writer has investigated the egg burster 

 in the Chrysopidae. It likewise is a specialized chitinous 

 apparatus situated on the thin embryonic cuticula and the 

 whole is shed at hatching. The molt was observed to with- 

 stand the action of heated caustic potash without injury and is 

 undoubtedly chitinous. The writer concluded from a rather 



Fig. 

 Fig. 



Fig. 1. 



A micropyle of an egg of Corydalis cornuta highly magnified. 

 Ventral aspect of an egg of Corydalis cornuta ready to hatch. Note the 

 large mandibles, the two ocellar fields and the absence of an_egg burster 

 in the mid ventral cephalic region. 



brief study of the embryology of the Chrysopidae that the 

 amnion was ruptured during the development of the embryo 

 and was drawn into the mid-intestine with the last of the yolk 

 to disintegrate or be absorbed. So the statement that they are 

 generally if not always on the amnion can not be accepted in the 

 light of later research. All egg bursters so far recorded are on a 

 chitinous embryonic cuticula, which in most cases is shed at 

 hatching as for example in the Chrysopidae, Hemerobiidae, 

 Pentatomidae, Trichoptera and the Psocidae. Lepisma and the 

 Pulicidae are said to retain the egg bursters for a day or longer, 



