ART. 6 FORAMINIFERA: POLYMORPHINIDAE — CUSHMAN AND OZAWA 9 



recognize the striking difference in arrangement of chambers between 

 Jurassic globular Polymorphinidae and Cretaceous and Tertiary 

 Globulina. For example, we may note Glohulina laevis Schwager 

 from the Lower Oxfordian ^ and Polymorphina gibbosa Terquem from 

 the Fuller's Earth. They are oval forms, having a few chambers 

 which are arranged in a quite diffei*ent series from the arrangement 

 of chambers in Globulina gibba. In both species each succeeding 

 chamber apparently becomes smaller and smaller, and the chambers 

 are arranged in a spiral series. Such globular, spiral forms are 

 evidently derived from other primitive Jurassic spiral forms by 

 having more overlapping and somewhat regularly triserial chambers. 



The fusiform P. liassica is also similar to species of Cretaceous and 

 Tertiary fusiform Globulinas such as Globulina prisca and G. minuta 

 in its general outline, and it is apparently impossible to separate 

 them. However, it may be considered that there are probably some 

 globular or fusiform Polymorphinidae in the Jurassic and Cretaceous 

 derived directly from the primitive spiral group. 



There is only one species of the Polymorphinidae described from 

 the Jurassic which may be placed under Guttulina with some doubt. 

 That is an ovate, somewhat compressed Polymorphina pygmaea 

 Schwager reported from the lower Oxfordian in Germany. It is 

 quite different from any of the other hitherto known Jurassic species 

 and somewhat resembles Guttulina lactea, but the chambers are 

 arranged in a clockwise series. The biserial species appear also to be 

 rare. Excepting for very doubtful P. imbricata, already noted, 

 Polymorphina sinuata Terquem is the only species having a compressed 

 test and biserial chambers. It evidently differs from more advanced 

 biserial Pseudopolymorphina and Polymorphina which are derived 

 from Guttulina and Sigmomorphina, respectively. It may be derived 

 directly from some Jurassic spiral group. Some Cretaceous biserial 

 species such as Polymorphina pleurostomelloides and P. gaultina are 

 undoubtedly related to Jurassic biserial forms. 



There are some ambiguous species described from the Jurassic, 

 such as P. annulata, P. oviformis, and P. septata, etc. They are 

 either doubtful Polymorphinidae or abnormal species. Spiral and 

 tetraloculine Polymorphinidae seem to have disappeared in the Lower 

 Cretaceous. We have a spiral species from the Gault in England 

 which is new. The two tetraloculine species described by Chapman 

 are also from England. 



These primitive Polymorphinidae are replaced by the more 

 advanced Guttulina, which becomes rather common in both Lower and 

 Upper Cretaceous, as do Pyrulina and Globulina as well. Guttulina 

 having the elongate quinqueloculine arrangement of chambers may 



3 Jahresh. Ver. vat. Nat. Wurtt., vol. 21, 1865, pi. 7, fig. 7. 



