10 BULLETIN 11, UNITED STATES NATIONAL MUSEUM. 



which are visible from the exterior, showing clearly in the last-formed 

 chambers from the ventral side; somewhat umbilicate ventrally; 

 walls comparatively thin and translucent; aperture somewhat 

 elongate situated at the inner border of the chamber. 



Diameter 0.138-0.636. 



Distribution. — The only North Pacific records for this species are 

 given by Rhumbler who found it in material from Laysan and from 

 Chatham Island, one specimen from each locality. 



Genus DISCORBIS Lamarck, 1804. 



Discorbis Lamarck (type, D. vesicularis Lamarck), Ann. Mus., vol. 5, 1804, p. 183. 

 Discorbites Lamarck, Ann. Mus., vol. 5, 1804, p. 183. 



Discorbina Carpenter, Parker and Jones, Introd. Foram., 1862, p. 203. — H. 

 B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 641. 



Description. — Test free or attached, spiral and rotaliform, plano- 

 convex or biconvex, or modified variously in different species; 

 typically plano-convex with the ventral side flattened and the 

 dorsal convex; all chambers visible from the dorsal side, only those 

 of the last-formed coil visible from the ventral side; test composed 

 of several coils, usually three or four in the adult test; chambers 

 rather numerous; aperture a slit at the umbilical margin of the 

 ventral side of the chamber. 



The various species of this genus show a considerable range of 

 characters, some of them such as D. tabernacularis being very different 

 from the typical form. As a rule they seem to be most common 

 in comparatively shallow water, and for this reason undoubtedly 

 the number which I have had is comparatively small as most of the 

 Albatross and Nero material has come from rather deep water. 



DISCORBIS TURBO (d'Orbigny). 



Plate 11, fig. 2. 



Rotalia (TrocMdina) turbo d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 274, No. 39; 

 Modeles, No. 73. — Parker, Jones, and H. B. Brady, Ann. Mag. Nat. Hist., 

 ser. 3, vol. 16, 1865, p. 30, pi. 2, fig. 68.— Basset, Ann. Soc. Sci. Charente 

 Inf., 1884 (1885), p. 162, fig. 



Rotalia turbo Jones and Parker, Quart. Journ. Geol. Soc, vol. 16, 1860, p. 306. 



Discorbina turbo Carpenter, Parker, and Jones, Introd. Foram., 1862, p. 200. — ■ 

 BtJTSCHLi, in Bronn, Klassen und Ordnungen Thier-Reichs, vol. 1, 1880, 

 p. 206, pi. 9, fig. 10.— Terrigi, Atti Accad. Pont. Nuovi Lincei, vol. 35, 1883, 

 p. 193, pi. 3, figs. 35, 36. — H. B. Brady, Rep. Voy. Challenger, Zoology, 

 vol. 9, 1884, p. 642, pi. 87, figs. 8a-c. — Egger, Abhandl. kon. bay. Akad. 

 Wiss. Miinchen, CI. n, vol. 18, 1893, p. 389, pi. 15, figs. 42-44.— Chapman, 

 Journ. Roy. Micr. Soc, 1896, p. 591, pi. 13, fig. 13.— Millett, Journ. Roy. 

 Micr. Soc, 1903, p. 697.— Bagg, Bull. U. S. Geol. Surv., No. 513, 1912, p. 81. 



Description. — Test plano-convex; dorsal surface conically rounded, 

 ventral side flat or very slightly convex; peripheral margin rather 



