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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 77 



be taken as an original stock from which various Tertiary and Recent 

 specialized genera having different arrangements of chambers arose. 



180' 



S" i 



1 '4 



9 



Figure 1. — Idealized basal views of various genera of the Polymorfhinidae to show the 



ARRANGEMENT OF CHAMBERS. O. EOGUTTULINA (SPIRAL). 6. QUADRULINA (TETRALOCUUNE). d. 

 PALEOPOLYMORPHINA (SPtaAL-BXSERIAL) . €, «'. GUTTULINA; €, CLOCKWISE QUINQUELOCULINEJ «', 

 CONTRACLOCKWISE QUINQUELOCULINE. /,/'. GlOBULINA; /, MICROSPHERIC form; /', MEGALOSPHERIC 



FORM. g. Pyrulina (quinqueloculine-biserial). h. Glandulina (biserial-uniserial). i. 



PSEUDOPOLYMORPHINA (quinqueloculine-biserial). j, ft. SiGMOMORPHINA, SiGMOIDELLA (.SIG- 

 MOID AL); j, CLOCKWISE; <r, CONTRACLOCKWISE. I. POLYMORPHINA (BISERIAL) 



Guttulina is characterized by a quinqueloculine arrangement of 

 chambers, and each succeeding chamber is added upwardly, so that 

 all apertures are directed toward one end. Its chambers are added 

 in planes 144° apart from one another. 



