FORAMINIFEEA OF THE MINT SPRING (CALCAREOUS MARL. 



139 



Rotalia dentata Parker and Jones var. parva Cushman, 

 n. var. 



Plate XXXV, figures 1 , 2. 



Variety differing from the typical species in 

 the size and the number of chambers, having 

 usually but five chambers in the last-formed 

 coil, each with a single spine from the peri- 

 phery at the center of each chamber. Diam- 

 eter 0.65 millimeter. 



Type specimen from station 6451, Mint 

 Spring Bayou, Vicksburg, Miss. This also oc- 

 curs at the following stations: 



6447, fi448. Glass Bayou, ^'icksburg, Miss. 

 6452. Mint Spring Bayou, ^'icksl)urg, Miss. 



Rotalia vicksburgensis Cushman, n. sp. 



Plate XXXA', figures :'.. 4. 



Test spiral, dorsal side flattened, ventral 

 side strongly convex, umbilicate, about eight 

 chambers in the last-formed coil; chambers 

 distinct, inflated; sutures distinct, slightly 

 depressed; surface smooth, finely punctate. 

 Diameter 0.75 millimeter or less. 



Type specimens from station 6647, Chicka- 

 sawhay River l{ miles southwest of Boice, 

 Miss. It also occurred at the following sta- 

 tions : 



6448. Glass Bayou, Vicksburg, Miss. 



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

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



This species is apparently related to R. solda- 

 nii D'Orbigny, but it does not have nearly so 

 great a height, the line between adjacent 

 whorls is not channeled, and in general it has 

 a much more primitive form. 



Family NUMMULITIDAE . 



Genus NONIONINA D'Orbigny. 1826. 



Nonionina umbilicatula (Montagu ) Parker, Jones, and 

 H. B. Brady. 



Nautilus umbihcatulus Montagu, Testacea Britannica, 



p. 191, 1803; Suppl., p. 78, pi. 18, fig. 1, 1808. 

 Nonionina umbilicatula (Montagu) Parker, Jones, and 

 H. B. Brady, Annals and Mag. Nat. Hist., 4th eer., 

 vol. 8, p. 242, pi. 12. fig. 157, 1871. 

 H. B. Brady, Challenger Rept., Zoology, vol. 9, p. 726, 



pi. 109, figs. 8, 9, i884. 

 Cushman, U. S. Geol. Survey Prof. Paper 129, p. 100, 

 pi. 23, figs. 3, 4, 1922. 



Test biconvex, peripheral margin rounded; 

 chambers ten or more in the last-formed coil; 

 sutures limbate but not depressed, deep, 



umbilicate; wall smooth, punctate toward 

 the periphery; aperture a very narrow curved 

 opening at the base of the chamber, peripheral. 

 Diameter 0.5 to 0.6 millimeter. 



Specimens that may be referred to this species 

 occurred at all but one of the Mint Spring 

 marl stations, as follows: 



6447, 6448. Glass Bayou, Vicksburg, Miss. 

 6452. Mint Spring Bayou, Vicksluirg, ^liss. 

 6647. Chickasawhay River 1^ miles southwest of Boice, 

 Miss. 



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



Specimens were not common, however, at 

 any of these stations. I have already recorded 

 the species from the Miocene near Center- 

 ville, Md. 



Nonionina scapha (Fichtel and Moll) Parker and Jones. 



Nautilus srapha Fichtel and Moll, Testacea microscopica 



p. 105, pi. 19, figs, d-f, 1803. 

 Nonionina scapha (Fichtel and Moll), Parker and .Tones 



Annals and Mag. Nat. Hist., 3d ser., vol. 5. p. 102 



No. 4, 1860. 

 H. B. Brady, Challenger Rept., Zoology, vol. 9, p. 7:-iO 



pi. 109, figs. 14, is", 16?, 1884. 

 Cushman, U. S. Nat. Mus. Bull. lO:^, p. 73, pi. 25, 



figs. 6a, b, 1918; U. S. Geol. Survey Prof. Paper 



129, p. 100, pi. 23, figs. 5-7, 1922. 



Test in side view longer than wide, about 

 ten chambers in the last-formed coil, rapidly 

 increasing in length as added; sutures evenly 

 curved, slightly depressed; periphery broadly 

 rounded, in apertural view the face of the last- 

 formed chamber making up a large part of the 

 visible surface; wall smooth, finely punctate, 

 somewhat umbilicate; aperture an arched 

 slit at the base of the chamber. Length 0.60 

 millimeter. 



Specimens of this species were more com- 

 mon than those of N. umhilicahiln. They 

 occurred at all but one of the stations in the 

 Mint Spring marl, as follows' 



6447, 6448. Glass Bayou, Vicksbiu-g, Miss. 



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



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



I have recorded the species as occurring in 

 the Gatun formation of the Canal Zone. 



Nonionina advena Cushman, n. sp. 



Plate XXXII, figure 8. 



Test small, circular in side view, biconvex; 

 periphery rounded, nine to eleven chambers in 

 the last-formed coil, inflated; sutures curved, 



