8 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.77 



in a spiral series, and each succeeding chamber is removed very much 

 farther from the base. Among them, P. polygona is the most inter- 

 esting, and Terquem put several forms with very diflt'erent appear- 

 ances in this species, some three chambered and compressed, the 

 others with an early stage similar to P. sacculus. We have a specimen 

 from the Kimmeridge clay in England which is very similar to 

 Terquem's first and second figures of P. polygona, and we have 

 identified it with Terquem's species; and it is described in the present 

 paper. In a certain position in side view the specimen is very much 

 like an elongated Guttulina, but the chambers are arranged in a spiral 

 series instead of a quinqueloculine one. 



Terquem's species Polymorphina distincta, P. amygdala, and P. 

 pyriformis are very similar to P. polygona in their arrangement of 

 chambers. 



From such spiral species are derived elongated forms such as 

 P. mutahilis (immutabilis) Schwager, P. pyriformis Terquem, P. 

 pupijormis Terquem, P. ovigera Terquem, P. quadrata Terquem, 

 and P. distincta Terquem. In these species chambers are arranged 

 in a spiral, and each succeeding chamber is r-emoved much farther 

 from the base, giving to the test an appearance of having a somewhat 

 uniserial or biserial arrangement of chambers. 



In such species as Polymorphina cruciata Terquem, P. lagenalis 

 Terquem, and probably P. squammata. Terquem, and P. angustata 

 Terquem, the chambers are added in planes 90° apart from one 

 another, and accordingly they are tetraserial. P. irregularis Ter- 

 quem may represent an intermediate form between such tetraserial 

 forms and the spiral species above referred to. Two such tetraserial 

 forms are reported by Chapman from the Lower Greensand in 

 England (Littleton, Bargate Bed of Surrey). They are Polymor- 

 phina rhabdogonioides and P. frondicularioides, both of which are 

 figured on Plate 1 of this paper. Chapman added in the description 

 that he thinks that they may represent a new genus or subgenus. 



Polymorphina imbricata Terquem is a cylindrical form with cham- 

 bers seemingly arranged in a biserial series, but we doubt if it is a 

 truly biserial species. 



One of the most important groups among the Jurassic Polymor- 

 phinidae is that having globular or fusiform species with the sutures 

 not depressed and chambers arranged in a nearly triserial spiral 

 series. In this group are included Polymorphina liassica Strickland, 

 P. fontinensis Terquem, Globulina laevis Schwager, Guttulina similis 

 Terquem and Berthelin, and several others. The globular species 

 such as P . fontinensis and Guttulina similis are few chambered forms, 

 and in their general outline they are very similar to Cretaceous and 

 Tertiary Globulinas such as Globulina lacrima and G. gibba. But if 

 we examine in detail figures of Jurassic globular forms, we can easily 



