FORAMINIFERA OF THE ATLANTIC OCEAN 39 



1895, p. 43. — SiLVESTRi, Atti Accad. Sci. Acireale, vol. 7, 1896, p. 90. — 

 Flint, Ann. Rep't. U. S. Nat. Mus., 1897 (1899), p. 332, pi. 75, fig. 4.— 

 SiLVESTRi, Mem. Pont. Accad. Nuovi Lincei, vol. 6, 1899, p. 328, pi. 6, 

 fig. 14. — KiAER, Rep't. Norwegian Fish, and Mar. Invest., vol. 1, No. 7> 

 1900, p, 47. — FoRNASiNi, Mem. Accad. Sci. Istit. Bologna, ser. 5, vol. 10, 

 1902, p. 60, text fig. 59.— Millett, Journ. Roy. Micr. Soc, 1904, p. 503.— 

 Chapman, Trans. New Zealand Instit., vol. 38, 1905 (1906), p. 106; 

 Journ. Quekett Micr. Club, ser. 2, vol. 10, 1907, p. 140.— Bagg, Proc. 

 U. S. Nat. Mus., vol. 34, 1908, p. 163. — Chapman, Subantarctic Islands 

 of New Zealand, 1909, p. 362; Journ. Linn. Soc. Zool., vol. 30, 1910, 

 p. 423; Zool. Res. Endeavour, pt. 3, 1912, p. 311. — Pearcey, Trans. Roj'. 

 Soc, Edinburgh, vol. 49, 1914, p. 1,030.— Cushman, Bull. 71, U. S. Nat. 

 Mus., pt. 5, 1915, p. 71, pi. 29, fig. 1; pi. 31, fig. 4. — Heron-Allen and 

 Earland, Trans. Zool. Soc. London, vol. 20, 1915, p. 719. — Chapman, 

 Biol. Res. Endeavour, vol. 3, pt. 1, 1915, p. 33. — Cushman, Proc. U. S. 

 Nat. Mus., vol. 56, 1919, p. 631; Bull. 100, U. S. Nat. Mus., vol. 4, 1921, 

 p. 349, pi. 71, figs. 2 a-c. — Heron-Allen and Earland, British Ant- 

 arctic Exped., Zoology, vol. 6, 1922, p. 219. — Yabe and Hanzawa, Jap. 

 Journ. Geol. Pal., vol. 4, 1925 (1926), p. 52.— R. E. and K. C. Stewart, 

 Journ. Pal., vol. 4, 1930, pi. 8, figs. 9 a-c; pi. 9, figs. 1 a-c. 



Test plano-convex, dorsal side flat or even slightly depressed, the 

 outer portion toward the periphery often channelled, ventral side 

 very convex, umbilicus deeply excavated, periphery rounded; cham- 

 bers fairly distinct, but often somewhat hidden on the dorsal side by 

 the calcareous thickening, width of the whorl variable; sutures fairly 

 distinct, those of the dorsal side in the early stages nearly radial 

 becoming more oblique in the adult, usually slightly oblique, those 

 of the ventral side radial, very little if at all depressed; wall thick, 

 smooth and often polished, about the umbilicus sometimes granular; 

 aperture, an elongate slit at the ventral border of the chamber usually 

 about halfway between the umbilicus and periphery, sometimes with 

 a slightly thickened border. 



Diameter up to about 2 mm. 



This is a very common species in the Albatross dredgings from the 

 Western Atlantic. It has a heavy, thickened test and is very white 

 and often highly polished. The early stages are often quite single 

 with a smooth test, rounded periphery and no channelling of the 

 dorsal surface (pi. 8, fig. 3). In the adult there is often considerable 

 variation in the same sample. The last whorl of chambers may be 

 narrow (pi. 8, fig. 6) or somewhat flattened and wader. The whorl 

 itself may come above the previous ones or may come well below 

 (pi. 8, fig. 6). The early stages have been referred to d'Orbigny's 

 G. laevigata by some authors. 



The fossil records have for the most part not been included in the 

 above references as many of them evidently do not belong to this, 

 species. 



2305—31 4 



