CLASSIFICATION 49 



many diverse forms (PL 13). These developed early in the 

 Palaeozoic and many of the complex ones developed there did not 

 persist to later times. Some of the arenaceous groups 



developed complex forms such as seen in the Fusulinidae, the 

 Orbitolinidae, and the Loftusiidae, but all have become extinct. 



The Miliolidae started their development in the Palaeozoic, 

 but did not reach their height until the Upper Cretaceous. They 

 had the power of adding arenaceous material to the outside of 

 the calcareous test in the earlier, more primitive forms, but lost 

 it in the more specialized ones. The calcareous test is imper- 

 forate. There are characters such as in the pseudopodia and 

 color of the protoplasm w^hich may help to show the distinctions 

 in this group even more plainly than at present. 



In the Lagenidae which have kept to a planispiral form of 

 coiling and then straightening out there is a primitive group 

 which reached its height in the Jurassic but still continues as 

 a plastic group showing practically no new developments in 

 later times. 



A general group of families in which the test is planispiral or 

 modifications from it, is seen in the lines leading to the 

 Peneroplidae which became imperforate and the Camerinidae 

 which continued the perforate character. Both of these special- 

 ized families reached the climax of their development in the 

 Eocene. 



The other two great groups developed from elongate spires, 

 more or less cylindrical in the Buliminidae and a flaring conical 

 type in the Rotaliidae. The Buliminidae have their beginnings 

 as far back as the Jurassic and have developed along many dif- 

 ferent lines usually terminating in a rectilinear uniserial test. 

 These are abundant in the Tertiary and have many varied forms 

 in the present ocean. 



The Rotaliidae and the families derived from it are all per- 

 forate and calcareous. The simpliest forms perhaps go back to 

 the Palaeozoic although the early records are very doubtful. In 

 the Jurassic they have a few primitive forms, reaching their 

 real development in the Cretaceous and Tertiary. From the 

 Rotaliidae have developed several families, some very interesting 

 in their adaptions. The Globigerinidae and Globorotaliidae have 

 become specially adapted to a pelagic life with many modifica- 

 tions. The young of the highly globose, very spinose 



