18 FORAMINIFERA 



in many genera of these families is developed an "apertural 

 chamber" or small cavity, the inner aperture into the main body 

 of the chamber being simple and the outer one radiate. 



In general the aperture is one of the features of the test most 

 worthy of study both in its adult form and in the successive 

 changes in the development of the earlier stages. 



