rORAMINIFERA OF THE MINT SPEINC CALCAKEOUS MARL. 



135 



characteristic of the lower OUgocene of the 

 Coastal Plain of the United States. 



The young of tliis species lias only a single 

 row of pits, becoming double in the adult. 

 The ornamentation of the ventral side is shown 

 in figure 5. 



Genus PATELLINA Williamson, 1858. 

 PatelUna advena Cushman. n. sp. 



Plate XXXI, figure !l. 



Test plano-convex, early portion composed 

 of chambers spirally arranged, later ones 

 elongate and becoming nearly amiular; cham- 

 bers partly divided by numerous longitudinal 

 internal septa, visible from tlie exterior, form- 

 ing what seems to be a radiating pattern; 

 ventral side with numerous radiating lines. 

 Diameter 0.4 millimeter. 



Type specimen from station 6452, Miiit 

 Spring Bayou, Vicksburg, Miss. 



This species differs from PatelUna corriKjata 

 Williamson in the much finer division by 

 internal septa. The spire is low, making a 

 broad, flaring test. 



Genus DISCORBIS Lamarck, 1804. 

 Discorbis auracana (D'Orbigny) Cushman. 



Plate XXXII, figiu-e G. 



Roftdlinn inirncmw D'Orbigny, Voyage dans r.-Vin^riqae 



m^ridionale, Foraniinifferes, p. 44, pi. 6, figs. 1(5-18, 



1839. 

 Discorbis auracana (D'Orbigny) Cushman, U. S. Nat. Mas. 



Bull. 71, pt. 3, p. 1.5, pi. 9, fig. 3; fig. 15 (in text). 

 Discorbina uurucaiw (D'Orbigny) Parker and Jones, Gool. 



Soc. London Quart. Jour., vol. 28, p. 11.5, 1872. 

 II. B. Brady, riiallrrit/cr Rcpt., Zoology vol. 9, p. G4.5, 



pi. 80, figs. 10, 11, 1884. 



Test small, plano-convex, dorsal side slightly 

 convex, ventral side flat or slightly concave, 

 peripheral margin rather acutely rounded; 

 chambers six to nine in the last-formed whorl; 

 sutures slightly depressed, often limbate with 

 clear shell material; early chambers often 

 carinate viith. similar material; wall finel.v 

 punctate; aperture a narrow curved slit at the 

 margin of the ventral side of the chamber; 

 color brownish, especially in the earlier cham- 

 bers. Diameter 0.3 to 0..5 millimeter. 



Specimens that are referred to tliis species 

 were rare at a single station, 6447, Glass 

 Bayou, Vicksburg, Miss. The sutures are 

 Umbate, and the last-formed chamber has a 

 projecting lip above the aperture. 



Discorbis bertheloti (D'Orbigny) Cushman. 



Plate XXXII, figure 7. 



Rosalina hrrthdoli D'Orbigny, in P>arker. Webb, and 



Berthelot, Histoire natiu'elle des iles Canaries, vol. 



2, pt. 2, Foraminifferes, p. 13.5, pi. ], figs. 28-.30, 



1839. 

 Discorbis berthdoli (D'Orlugny) Cushman, U. S. Nat. 



Mus. Bull. 71, pt. 3, p. 20, pi. 7, fig. 3, 1913; U. S. 



Oeol. Sui-vey Bull. 670, p. 58, pi. 15, figs. 1-3, 1918. 

 Discorbina bertheloti (D'Orbigny) If. B. Brady, Linnean 



Soc. London Trans., vol. 24, p. 409, pi. 48. figs. 10a. I), 



1804 ; riiallrnger Rept., Zoology, vol. 9, p. 050. i)l. 89. 



figs. 10-12, 1884. 



Test unec[ually bic(mve.x, usually six to 

 seven chambers in the last-formed coU, dorsal 

 side usually flattened, ventral side more convex; 

 sutures curved, fairly distinct on both sides, 

 occasionally slightly Ihnbate; aperture usually 

 extending into the dorsal si(ki so that a por- 

 tion of the aperture is peripheral. Diameter 

 0.80 millimeter or less. 



This species occurs at two Mint Spring marl 

 stations : 



0451, 0452. Mint Spring Bayou, Vicksliurg, Miss. 



I have also recorded it from the Miocene of 

 the Coastal Plain in the Choctawhatchee marl 1 

 mile south of Red Bay, Fla. ; in the Duplin 

 marl ( '<) of South Carolina (locality unknown) ; 

 and in the Yorktown formation at Suft'olk, ^'a. 



Genus TRUNCATULINA D'Orbigny, 1826. 

 Truncatulina lobatula (Walker and Jacob) D'Orbigny. 



Nautilus lohaliihis Walker and Jacob, .' dams's Essays on 

 the microscope, Kanmacher's cil., p. 042, jil. 14, 

 fig. 30, 1798. 



Triiiicatiilina lobatula (Walker and Jacob) D'Orbigny, in 

 Barker, Weblj, and Berthelot, tlistou'e natui'elle des 

 lies Canaries, vol. 2, pt. 2, Foraminifferes, p. 134, 

 pi. 2, figs. 22-24, 1839; Foraminiferes fossiles du 

 l>as.sin lertiaire de Vienne, p. 108, pi. 9. figs. 18-23, 

 1840. 

 H. B. Brady, Challenger Rept., Zoology, vol. 9, p. 000, 



pi. 92, fig. 10; pi. 93, fig. 1, 1884. 

 Cushman. U. S. Geol. Survey Bull. 070, p. 10, pi. 1, 

 fig. 10; p. 60, pi. 17, figs, i-3; U. S. Geol. Survey 

 Prof. Paper 129, p. 26, pi. 20, figs 1-3, 1922. 



Test plano-convex, flattened on the ventral 

 face, moderately convex dorsally, peripheral 

 margin rounded; chambers numerous, seven 

 or eight in the last-formed whorl; sutures 

 depressed, especially on the dorsal face; wall 

 smooth, punctate. 



