200 FORAMINIFERA 



in a clockwise sigmoid series at least in the early stages of the 

 microspheric form, later becoming biserial in the microspheric 

 form or entirely so in the megalospheric ; sutures depressed or 

 not, often limbate. 



Genus SIGMOMORPHA Cushman and Ozawa, 1928 



Plate 26, figures 11, 12 

 Genoholotype, Sigmomorpha sadoensis Cushman and Ozawa 



Sigmomorpha Cushman and Ozawa, Contr. Cushman Lab. Foram. Res., 



vol. 4, 1928, p. 17. 

 Polymorphina (part) of authors. 



Test flattened, oval to subelliptical in side view; chambers 

 elongate, angular in transverse section, arranged at first like 

 Guttulina, then open sigmoidal; sutures distinct, depressed. 



This genus may be divided into two subgenera: 



Siginomorpha s. str. 



Rounded chambers are arranged in a more or less closed 

 sigmoid series, and five or six chambers of each series complete 

 one cycle. 



Sigmomorphina Cushman and Ozawa, 1928. 



Subgenotype, Sigmomorphma yokoyamai Cushman and Ozawa. 



Sigmomorphina Cushman and Ozawa, Contr. Cushman Lab. Foram. 

 Res., vol. 4, 1928, p. 17. 



Chambers much compressed, triangular in section and the 

 successive chambers added in planes of more than 180°, often 

 much twisted. 



Genus SIGMOIDELLA Cushman and Ozawa, 1928 



Plate 26, figures 13-15 

 Genoholotype, Sigmoidella kagaensis Cushman and Ozawa 

 Sigmoidella Cushman and Ozawa, Contr. Cushman Lab. Foram. Res., 



vol. 4, 1928, p. 18. 

 Polymorphina (part) of authors. 



Test ovate to elliptical in side view, compressed; chambers 

 elongate, angular, regularly arranged in open sigmoid series, 

 gradually increasing in length in the later ones which include 

 the earlier ones, but often the adult chambers not reaching the 

 base; sutures distinct. 



The following two subgenera may be distinguished : 



Sigmoidella s. str. 



