FORAMINIFERA OF NORTH PACIFIC OCEAN. 27 



Apparently this specimen is megalospheric, as the chambers 

 immediately succeeding the proloculum are arranged biserially, with 

 no trace of a coiled series of chambers. The species is a large and 

 striking one. 



Genus BIGENERINA d'Orbigny, 1826. 



Bigenerina d'Oebigny (type, B. nodosaria d'Orbigny), Ann. Sci. Nat., vol. 7, 

 L826, p. 261. — H. 15. Brady, Rep. Voy. Challenger, Zoology, vol. !), 1884, 

 p. 368. 



Description. — Test free, elongate, composed of a series of biserial 

 chambers in the early portion, followed by several chambers uniseri- 

 ally arranged; aperture typically an oval or rounded opening near the 

 middle of the terminal face; walls fairly thick, arenaceous, usually 

 fairly coarse, but sometimes of fine material and smooth. 



The specimen figured originally by d'Orbigny is rather charac- 

 teristic. It has twelve biserially arranged chambers followed by a 

 uniserial series of four chambers. In his sectional figure d'Orbigny 

 shows the apertures of the early portion as truly textularian on the 

 border of the inner margin of the apertural face, between it and the 

 preceding chamber, while in the uniserial chambers it becomes a 

 central opening in the middle of the terminal face of the chamber. 



Later authors have included in this genus a great variety of species 

 with characters not in accord with those established by d'Orbigny. 

 Brady, in his synonymy, gives a long list of genera which he places 

 wholly or in part in this genus. 



As shown in B. arenacea Bagg, there are apparently both megalo- 

 spheric and microspheric forms present. In the microspheric form 

 the early chambers following the proloculum are coiled, as in the 

 microspheric form of various species of Textularia, and like both forms 

 in Spiroplecta. Later chambers are biserially arranged, as in Textu- 

 laria, and those of the last formed group are arranged uniserially, 

 giving the generic character. In the megalospheric form the coiled 

 chambers may be wanting. As in other types, the microspheric 

 form of the species attains the larger size. 



BIGENERINA NODOSARIA d'Orbigny. 



Bigenerina nodosaria d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 261, pi. 11, figs. 



9-11; Modeles, 1826, No. 57. — Parker, Jones, and H. B. Brady, Ann. Mag. 



Nat. Hist., ser. 3, vol. 16, 1865, p. 28, pi. 2, fig. 62.— Terrigi, Atti. Ace. Pont. 



Nuovi Lincei, vol. 33, 1880, p. 192, pi. 2, fig. 28.— H. B. Brady, Rep. Voy. 



Challenger, Zoology, vol. 9, 1884, p. 369, pi. 44, figs. 14-18.— Wright, Proc. 



Roy. Irish Acad., ser. 3, vol. 1, 1891, p. 471. — Goes, Kongl. Svensk. Vet. 



Akad. Handl., vol. 25, No. 9, 1894, p. 37, pi. 7, figs. 313-315 [316-323?]; Bull. 



Mus. Comp. Zool., vol. 29, 1896, p. 44.— Flint, Ann. Rep. U. S. Nat. Mus., 



1897 (1899), p. 286, pi. 31, fig. 4.— Millett, Journ. Roy. Micr. Soc, 1899, p. 



564, pi. 7, fig. 13. 

 Textularia agglutinins, var. nodosaria Parker and Jones, Philos. Trans. Roy. 



Soc, vol. 155, 1865, p. 371, pi. 15, fig. 25; pi. 17, fig. 80. 

 Clavulina elegans Karrer, Norara Exped., Geol. Theil, vol. 1, 1864, p. 80, pi. 



16, fig. 11. 



