50 FORAMINIFERA 



Globigerinidae in the microspheric form is a trochoid, smooth, 

 more or less flattened Discorbis-like form, showing the early 

 ancestry of this group. 



Some groups become attached and like the Homotremidae and 

 Rupertiidae have developed peculiar forms which except that 

 their early stages are trochoid forms like others of the Rotaliidae 

 would hardly be classed with the rest of the foraminifera. 

 Finally in the Orbitoididae there are complex large forms de- 

 veloped, which in the late Cretaceous and early Tertiary become 

 very much specialized. These form excellent guide fossils for 

 various formations during this particular time. 



By taking into consideration the various stages in develop- 

 ment, especially in the microspheric forms and the known 

 geologic history of each group the following classification of the 

 foraminifera has been developed. That it is perfect is not for 

 a moment claimed, but that it is based upon known truth in 

 regard to the past and present history of the group and on 

 developmental stages makes it at least nearer the truth than the 

 more artificial ones that have preceded it. 



