NO. 1 CUSHMAN, MCCULLOCH : ARENACEOUS FORAMINIFERA 107 



face highly convex, exhibiting all convolutions, which are slightly 

 'stepped' one below another. Ventral surface nearly flat but with a 

 deeply sunk umbilicus, exhibiting only the chambers of the final convo- 

 lution. Sutural lines recurved on dorsal side, straight on ventral, slightly 

 depressed. Peripheral edge subacute. Aperture a small slit on inner edge 

 of final chamber on ventral side. Constructed of very fine sand with 

 much cement. Colour dark ferruginous brown, sometimes nearly black, 

 but occasionally lighter. Surface smooth but not highly polished." 



Diameter 0.20-0.35 mm; height 0.12-0.18 mm. 



Earland described this species from the Falklands sector of the Ant- 

 arctic. We have a very similar form in our material from the cold 

 water of the eastern Pacific at a number of localities. Our specimens 

 are minute but average a little larger than the measurements given by 

 Earland. The ventral surface is much flatter than T. vesicularis Goes 

 and the spire much lower. T. discorbis occurs at the following stations: 

 2065, 2005, 275, 2063, 2029, 2024, 2070, 583, 2057, A-1, 1046, 2063, 

 332, 299, 283, 226, 106, 113, 285, 268, 227, 258, 284, 534, 413, 420, 

 460, 461, 465, 471, 506, 223, 275, 2024, 2033, 1037, 2037, 299, 456, 

 258, 416, 473, 466, 462, 459, 456, 418, 410, 409, 557, 547, 553, 555, 

 519, 539, 532, 517, 501. 



Distribution. — From Ketchikan, Alaska, in 8 fms. to Octavia Bay, 

 Colombia, in 50 fms., with numerous intermediate stations for the Gulf 

 of California, and for the Galapagos Islands. 



Trochammina rotaliformis J. Wright 

 Plate 12, Fig. 2 



Trochammina inflata (Montagu), var., Balkwill and Wright, Trans. 

 Roy. Irish Acad., vol. 28 (Science), 1885, p. 331, pi. 13, figs. 11, 12. 



Trochammina rotaliformis J. Wright, in Heron-Allen and Earland, 

 Journ. Roy. Micr. Soc, 1911, p. 309. — Heron-Allen and Earland, Proc. 

 Roy. Irish Acad., vol. 31, pt. 64, 1913, p. 52, pi. 3, figs. 11-13; Trans. 

 Zool. Soc. London, vol. 20, 1915, p. 620.— Cushman, Bull. 104, U. S. 

 Nat. Mus., pt. 2, 1920, p. 77, pi. 16, figs. 1, 2; Contrib. Canadian 

 Biol., 1921 (1922), p. 8.— Heron-Allen and Earland, Bull. Soc. Sci. 

 Hist. Nat. Corse, 1922, p. 126; British Antarctic Exped., Zoology, vol. 

 6, 1922, p. 114; Journ. Linn. Soc. Zool., vol. 35, 1924, p. 616. — Lacroix, 

 Compte rendu Congres Lyon, Assoc. Fr. Avan. Sci. 1926, p. 421, text- 

 fig. 5; Comptes rendus Acad. Sci., vol. 183, August 17, 1926, pp. 430, 

 431. — Heron-Allen and Earland, Journ. Roy. Micr. Soc, vol. 50, 



