FORAMINIFERA OF THE MINT SPRING CALCAREOUS MARL. 



137 



bers somewhat irregularly granular, especially 

 toward the inner margin; otherwise the cham- 

 bers are not distinct from one another. Diam- 

 eter 0.50 to 0.60 millimeter. 



Type specimen from station 6448, Glass 

 Bayou, Vicksburg, Miss. 



This differs from the other species of the 

 genus found in the lower Oligpcene of the 

 Coastal Plain in its form, its indistinct cham- 

 bers, and the peculiar ornamentation of the 

 ventral side. 



Genus ANOMALINA D'Orbigny, 1826. 



Anomalina bilateralis Cushman. 



Anomalina bihilcralis Cushman, U. S. Geoi. Survey Prof. 

 Paper 129, p. 97, pi. 21, fisjs. 1, 2, 1922. 



Test of about four coils, bilateral or nearly 

 so, composed of numerous chambers, ten or 

 more in the last-formed whorl, umbilical region 

 on both sides with a knob of clear shell material, 

 more pronounced on the dorsal side; chambers 

 Smooth but coarsely punctate, more coarsely 

 so on the ventral side ; sutures broad and some- 

 what limbate with clear shell material; aper- 

 ture a narrow curved opening at the base of 

 the final chamber. Diameter 1 millimeter or 

 less. 



This is one of the species described from 

 specimens collected in the Byram marl, where 

 it was rare, at least at the type station. In 

 the Mint Spring marl it occurred sparsely at the 

 following stations: 



C448. Glass Bayou, Vicksburg, Miss. 

 64.51. Mint Spring Bayou, Vicksburg, ^^ias. 

 6647. Chickasawhay River 1} miles southwest of Boice, 

 Miss. 

 7671. "Brown's Cave." Leaf River, Miss. 



Anomalina mississippiensis Cushman. 



Anomalina mississipj>iensis Cushman, U. S. Geol. Survey 

 Prof. Paper 129, p. 98, pi. 21, figs. 6-8, 1922. 



Test small, plano-convex, of about two and 

 one-half coils, periphery slightly lobulate, 

 bluntly rounded, dorsal side very much flat- 

 tened, even slightly concave, ventral side very 

 convex; chambers comparatively few, six to 

 eight in the last-formed coil; sutures curved, 

 on the dorsal side broad and limbate, even with 

 the surface of clear shell material, on the ven- 

 tral side narrower and depressed; the last- 

 formed two or three chambers on the inner 

 margin on the dorsal side slightly above the 

 general surface; wall thin and translucent, 

 especially on the dorsal side, smooth; on the 



ventral finely punctate and not so clear; aper- 

 ture a curved opening at the inner margin at 

 the periphery. Length 0.25 to 0.35 millimeter; 

 breadth 0.20 to 0.30 millimeter. 



This small species is fairly common in the 

 Byram marl and is common in the Mint Spring 

 marl at all the stations, as follows; 



6447, 6448. Glass Bayou, Vicksburg, Miss. 

 6451, 64.52. Mint Spring Bayou, Vicksburg, Miss. 

 6647. Chickasawhay River 1| miles southwest of Boice, 

 Miss. 

 7671. "Brown's Cave," Leaf River, Miss. 



Anomalina vicksburgensis Cushman, n. sp. 



Plate XXXV, figures 5, 6. 



Test unequally biconvex, dorsal side more 

 flattened than the ventral; chambers numer- 

 ous, ten to twelve in the last-formed coil; 

 sutures slightly limbate; periphery rounded, 

 not lobulate; wall between the sutures finely 

 granular or punctate, ventral side with a clear 

 mass of shell material at the umbilicus. Diam- 

 eter 0.35 millimeter. 



Type specimen from station 6452, Mint 

 Spruig Bayou, Vicksburg, Miss. This is a 

 peculiar species of the genus; it is rare at the 

 type station and was not found in any other 

 Mint Spring material. 



Genus SIPHONINA Reuss, 1849. 



Siphonina advena Cushman. 



Siphonina advena Cushman, U. S. Geol. Survey Prof. 

 Paper 129, p. 98, pi. 22, figs. 1-2, 1922. 



Test unequally biconvex, dorsal side usually 

 less convex than the ventral; periphery sub- 

 acute; chambers in three or more coils, four 

 chambers making up the last-formed coil; 

 sutures distinct, on the dorsal side flush with 

 the surface, on the ventral side slightly de- 

 pressed, on the dorsal side somewhat broad- 

 ened and limbate, ventrally narrow; surface 

 smooth but punctate; aperture with a short 

 neck, compressed, with a phialine lip and 

 elliptical aperture; color, even in the fossil 

 specimens, somewhat brownish; wall thin and 

 translucent. Diameter 0.50 millimeter or less. 



Specimens of this species occurred at all six 

 of the Mint Spring marl stations, as follows: 



6447, 6448. Glass Bayou, Vicksburg, Miss. 

 6451, 6452. Mint Spring Bayou, Vicksburg, Miss. 

 6647. Chickasawhay River IJ miles southwest of Boice, 

 Miss. 

 7671. "Brown's Cave," Leaf River, Miss. 



It was common in the marl at Byram, Miss. 



