118 PROCEEDINGS OF THE NATIONAL MUSEUM vol.77 



compressed, arranged in a regular biserial series, alternating almost 

 equally upon the two sides, slightly embracing, each succeeding 

 chamber removed farther from the base; sutures slightly depressed, 

 distinct; wall smooth; aperture radiate. 



Maximum length 1.25 mm.; breadth 0.95 mm.; thickness 0.15 mm. 



Polymorphina complanata is highly specialized and can be easily 

 distinguished from any other described species by its much compressed 

 and rhombic test. The arrangement of the chambers is also very 

 regular and entirely biserial, and a Guttnlina-like stage is skipped in 

 this species. 



Many forms are recorded as Polymorphina complanata from various 

 parts of the world, but are all different from the species described by 

 d'Orbigny from the Vienna Basin. 



Distribution. — The present species is only known from the Tortonian, 

 Amphistegina marl, at Grunes Kreuz, Nussdorf, near Vienna, where 

 it is fairly common. Ozawa collected more than 50 specimens from 

 this locality. D 'Orbigny reported its occurrence in the Tortonian clay 

 of Baden, but there is no original or paratype specimen of the present 

 species from Baden, and Ozawa could not find any specimen like the 

 present one in all the material he collected and prepared from that 

 locality. 



POLYMORPHINA ADVENA Cuslunan 



Plate 30, figures 10 a, b 



Polymorphina advena Cushman, U. S. Geol. Survey Prof. Paper 129-F, 

 1922, p. 132, pi. 31, fig. 4; Contr. Cushman Lab. Foram. Res., vol. 5, 

 1929, p. 41, pi. 7, fig. 5. 



Test much cdmpressed, broadly ovate; chambers numerous, elon- 

 gate, alternating, much the broadest near the peripheral end; sutures 

 slightly depressed, very oblique; surface ornamented with numerous 

 fine longitudinal costae, except the last-formed one or two chambers, 

 which are smooth, at least at the apertural end; aperture radiate. 



Length 0.40-0.65 mm.; breadth 0.22-0.30 mm.; thickness 0.05- 

 0.06 mm. 



Type specimen from the Lower Oligocene, Mmt Spring marl, 

 Mint Spring Bayou, Vicksburg, Miss. It is also known from the 

 Byram marl of Byram, Miss. 



This species is an unusual one for this genus, appearing much more 

 hke a Bolivina, but it has the characteristic aperture of Polymorphina. 

 It is perhaps most closely related to Polymorphina complanata 

 d'Orbigny. 



POLYMORPHINA FRONDEA (Cushman) 



Plate 30, figures 11 a, 6 



Bolivina frondea Cushman, XJ. S. Geol. Survey Prof. Paper 129-F, 1922, p, 



126, pi. 29, fig. 3; Prof. Paper 133, 1923, p. 20. 

 Polymorphina frondea Cushman, Contr. Cushman Lab. Foram. Res., vol. 5, 



1929, p. 41. 



