FORAMINIFERA 



199 



Test planispirally coiled or becoming straight, or single cham- 

 bered; fossil and recent Family 24 Lagenidae 



Genus Lagena Walker and Jacob (Fig. 77, c) 



Test biserial or elongate spiral; fossil and recent _ 



Family 25 Polymorphmidae 





L^iP^' 



f:&. J 



W. 





@ 



tu 



■' /f '..f^ 





Fig. 76 Diagram showing the development of Peneroplis pertusus.^ (After 

 Winter), a-f, megalospheric generation; g, gamete formation; h-k, 

 isogamy; 1-n, microspheric generation; o, multiple division. 



