24 



BULLETIN 104, UNITED STATES NATIONAL MUSEUM. 



Well characterized species of Bigenerina occur in the Tertiary from 

 the Eocene onward. In the Palaeozoic, especially in the Carboni- 

 ferous, specimens occur which may possibly belong generically to 

 Bigenerina, but their structure should be carefully studied to be sure 

 of this. At any rate they are closely allied in general form. 



BIGENERINA NODOSARIA d'Orbigny. 



Bigenerina nodosaria d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 2G1, pi. 11, figs. 

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

 Nat. Uist., 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, Ptep. Voy. 

 Challenger, Zoology, vol. 9, 1884, p. 369, pi. 44, figs. 14-18; Journ. Roy. Micr. 

 Soc, 1887, p. 895. — ^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?].— FoRNAsiNi, Mem. Accad. Sci. Bologna, ser. 

 5, vol. 10, 1901, p. 12; 1903, p. 142, pi. O, figs. 12, 13.— Cushman, Bull. 71, 

 U. S. Nat. Mus., pt. 2, 1911, p. 27, figs. 46-48 (in text); Bull. 100, U. S. Nat. 

 Mus., vol. 4, 1921, p. 125, pi. 26, fig. 2; Publ. 311, Carnegie Inst. Wash., 

 1922, p. 25, pi. 2, figs. 5, 6. 



Description. — Test elongate, subcylindrical, the early portion 

 somewhat compressed, consisting of a biserial group of chambers, 

 broader than the succeeding uniserial group, later portion cylindrical 

 or slightly tapering; chambers distinct, those of the early portion typi- 

 calfy more numerous than those of the uniserial portion, the latter 

 being 3-5 in number; sutures usually distinct, slightly depressed; wall 

 rather coarsely arenaceous with a grayish-white cement; aperture of 

 the early portions as in Textularia, an elongate slit between the base 

 of the inner margin of the chamber and the adjacent wall of the 

 preceding chamber, in the uniserial portion rounded and terminal; 

 color white or light gray. 



Length up to nearly 2 mm. 



Distrihution. — D'Orbigny described this species from the Adriatic 

 Sea. His Modele shows a rather smooth form. In typical European 

 material which I have seen from off the coast of the British Isles the 

 biserial compressed portion makes up usually one-third or more of 

 the total length of the chamber. It seems to be common about the 

 British Isles from the numerous records given above. In the western 

 Atlantic however it does not appear, at least in its typical form, and 

 is replaced by the following variety. 



