FOEAMINIFERA. 



Order V. ENALLOSTEGIA. 



13 



Polymorphina (D'Orb.). Shell with unequal 

 sides, without corresponding parts ; alternation of 

 the chambers upon two faces ; orifice round, ter- 

 minal. 



P. lactea. 



oblonga. Fig. 16 ; . 

 ? rotundata. 



Order VI. AGATHISTEGIA. 



Spiroloculina (D'Orb.). Shell equal-sided, formed 

 of corresponding parts ; chambers aggregated on 

 two opposing faces, all of them apparent, not 

 embracing. 



S. concentrica. Fig. 17 ; 'Y** 



