ART. 6 FORAMINIFERA: POLYMORPHINIDAE — CUSHMAN AND OZAWA 119 



Test compressed, of uniform thiclaiess, the broad sides nearly 

 parallel, oblong, broadest above the middle, acuminate toward the 

 initial end, margins with a raised rim; chambers compressed, elon- 

 gated, alternating; sutures depressed, distinct; wall smooth, often 

 with obscure fine costae; aperture radiate. 



Length 0.50-0.65 mm.; breadth 0.30-0.40 mm.; thickness 0.04- 

 0.05 mm. 



Polymorphina frondea is one of the most clearly marked species of 

 Polymorphina. Its raised margins are very characteristic, and no 

 other known species has such margins. Otherwise, it is closely 

 related to Polymorphina advena, which is always ornamented on its 

 surface and has a rounded periphery. 



Distribution. — The species is characteristic of the lower Oligocene of 

 the Coastal Plain region of the United States; Byram marl, Byram, 

 Miss. ; Glendon limestone, below waterfall in Glass Bayou, Vicksburg, 

 Miss.; west bank of Conecuh River at McGowan's Bridge, about 

 1 mile below the mouth of the Sepulga River, Ala.; Marianna lime- 

 stone, bluff east of small branch about Iji miles northeast of Brandon, 

 Miss. ; Mint Spring marl, Chickasawhaj^ River, 1 K miles northwest of 

 mouth of Limestone Creek, 4 miles northwest of Waynesboro, and 

 lYi miles southwest of Boice, Miss. ; Red Bluff clay, St. Stephen's Bluff, 

 right bank of Tombigbee River, about 9 miles above Jackson, Ala. 



POLYMORPHINA CHARLOTTENSIS Cushman 



Plate 31, figures 1-6 



Polymorphina charlotiensis Cushman, Contr. Cushman Lab. Foram. Res., 



vol. 1, 1925, p. 41, pi. 6, fig. 9. — Cushman and Ozawa, Jap. Journ. 



Geol. and Geogr., vol. 6, 1929, p. 72, pi. 13, fig. 8; pi. 15, figs. 11, 12; 



pi. 16, fig. 1. 

 Polymorphina compressa Cushman, Bull. 71, U. S. Nat. Mus., pt. 3, 1913, 



p. 89, pi. 40, fig. 3. 

 Polymorphina complanata Bagg (not d'Orbigny), Bull. 513, U. S. Geol. 



Survey, 1912, p. 69, pi. 20, figs. 13, 14. 

 Polymorphina biserialis Galloway and Wissler, Journ. Pal., vol. 1, 1927, 



p. 53, pi. 9, fig. 4. 

 Polymorphina elongata Galloway and Wissler, Journ. Pal., vol. 1, 1927, 



p. 54, pi. 9, fig. 7. 



Test elongate, more or less compressed, tapering slightly from the 

 broadly rounded initial end, edges more or less angular; chambers 

 compressed, not much elongated, arranged at first in a clockAvise, 

 sigmoid series in the microspheric form, but in an almost alternating 

 biserial series in the megalospheric form, each succeeding chamber 

 removed much farther from the base; sutures not depressed, generally 

 limbate and distinct; wall smooth, translucent; aperture radiate. 



Maximum length, 3.10 mm. ; breadth, 0.85 mm. ; thickness, 0.30 mm. 



Polymorphina charlotiensis is generally very large, attaining 3 

 millimeters in length. Bagg described and figured the present spe- 



