6 



BULLETIN 161, UNITED STATES NATIONAL MUSEUM 



Polystomella vortex Blainville, Man. Malac, p. 389, 1825. 



Robulina vortex d'Orbigny, Ann. Sci. Nat., vol. 7, p. 288, no. 4, 1826. 



Cristellaria vertex Parker, Jones, and H. B. Brady, Ann. Mag. Nat. Hist., ser. 

 4, vol. 8, p. 240, pi. 10, fig. 82, 1871.— H. B. Brady, Rep. Voy. Challenger, 

 Zoology, vol. 9, p. 548, pi. 69, figs. 14^16, 1884.— Flint, U. S. Nat. Mus. 

 Rep. for 1897, p. 317, pi. 65, fig. 1, 1899.— Bagg, Proc. U. S. Nat. Mus., 

 vol. 34, p. 148, 1908.— CusHMAN, U. S. Nat. Mus. Bull. 71, pt. 3, p. 68, 

 pi. 32, fig. 3, 1913. 



Test planispiral, close coiled, entirely involute, strongly biconvex, 

 peripheral end with a distinct keel; chambers numerous, 8 to 12, of 

 uniform shape and increasing only slightly in size as added, elongate, 

 strongly curved, usually not injQated; sutures distinct, strongly lim- 

 bate, very strongly curved, especially toward the inner end; wall 

 smooth, very finely perforate; aperture radiate, at the peripheral 

 margin, with a distinct, ventrally pointing slit in well-preserved 

 specimens, the side of the apertural face distinctly raised. Diameter, 

 up to 2.5 mm; thickness, up to 1 mm. 



This species is wddely distributed, although various specimens that 

 do not belong here have probably been referred to it by various 

 authors. It has not been common in our material, and occurred only 

 in Albatross collections from the deeper water stations. The data for 

 these are given in Table 4. 



Table 4. — Robulus vortex — material examined 



ROBULUS GIBBUS (d'Orbigny) 



Plate 2, Figures 2a, b, 6, 7 



Cristellaria gibba d'Orbigny, Ann. Sci. Nat., vol. 7, p. 292, no. 17, 1826; in de la 

 Sagra, Hist. Fis. Pol. Nat. Cuba, "Foraminiferes," p. 63, pi. 7, figs. 20, 

 21, 1839. 



Test very strongly biconvex, usually somewhat longer than broad, 

 the peripheral angle usually with only a slight keel, if any, close coiled, 

 the peripheral face somewhat concave with raised sides; chambers 

 numerous, 7 to 10 in the adult coil, elongate, strongly curved, of nearly 

 uniform shape throughout, increasing slowly in size as added; sutures 

 distinct, limbate, rather strongly and evenly curved; wall smooth, 



