FORAMINIFERA. 



13 



Order V, ENALLOSTEGIA. 



PolymorpMna (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 ; £. 

 1 rotundata. 



Order VI. AGATHISTEGIA. 



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

 of corresponding parts ; chambers aggregated on 

 two opposing faces, all of them apparent, not 

 embracing. 



S. concentrica. Fig. 17 ; 1°. 



