122 



BULLETIN 104, UNITED STATES NATIONAL MUSEUM 



Earland, Trans. Zool. Soc. London, vol. 20, 1915, p. 708. — Sidebottom, 

 Journ. Roy. Micr. Soc, 1918, p. 256. — Heron-Allen and Earland, 

 British Antarctic Exped. Zoology, vol. 6, 1922, p. 210. — Yabe and Han- 

 ZAWA, Jap. Journ. Geol. Pal., vol. 4, 1925 (1926), p. 52. 



Test unequally biconvex, dorsal side much flattened, dorsal side 

 showing all the whorls, ventral side somewhat evolute, periphery 

 bluntly angled; chambers very numerous, twelve to fifteen in the 

 adult whorl, of uniform shape, increasing in size very gradually; 

 sutures only slightly oblique on the dorsal side, more so on the ventral, 

 only slightly depressed on the ventral side; wall smooth, very trans- 

 parent so that all the chambers are visible to the center, especially 

 from the dorsal side, ver}^ finely perforate; aperture at the periphery 

 and extending slightly on both sides; color a rich brown. 



Diameter up to nearly 1 mm. 



This is a very distinctive species in its form and coloring. Its dis- 

 tribution seems to include other regions than the Atlantic, but it is 

 characteristic of cool waters or waters of some considerable depth. 



The wider spread form is not clearly made out, but some of the 

 forms assigned to Planulina may be found to connect with this 

 species. 



Cibicides robertsoniana — Material examined 



CIBICIDES FLORIDANA (Cushman) 



Plate 23, figures 3-5 



Truncatulina floridana Cushman, Bull. 676, U. S. Geol. Surv., 1918, p. 62, 

 pi. 19, figs. 2 a-c. — NuTTALL, Quart. Journ. Geol. Soc, vol. 84, 1928, p. 

 98, pi. 7, figs. 14, 16. 

 Cibicides floridana Cushman, Bull. 4, Fla. Geol. Survey, 1930, p. 61, pi. 12, 

 figs. 3o-c. 



Test biconvex to plano-convex, dorsal side normally the less convex, 

 periphery usuallj^ subacute, at least in the early stages; chambers 

 gradually increasing in size, of fairly uniform shape in each specimen, 

 number in the coil variable in typical specimens, ten to twelve; sutures 

 on the dorsal side usually limbate, oblique, not depressed except 



