DIMORPHINA TUBEROSA. 275 



DiMOEPHiNA TUBEEOSA, d'Orh., 1826. Anu. Sci. Nat., vol. vii, p. 264-, JSTo. 1 ; 



Modele, No. 60. 

 — NODOSAETA, d'Orb., 1846. Foram. Foss. Vien, p. 221, pi. xii, figs. 



21, 22. 

 Glandulina uefoemis, Costa, 1856. Atti Accad. Pontan., vol. vii, fasc. 2, p. 129, 



pi. xi, figs. 16—18, 26. 

 DiMOEPHiNA TUBEEOSA, FarJcer, Jones, and Brady, 1865. Ann. Mag. Nat. Hist., 



ser. 3, vol. xvi, p. 28, pi. ii, fig. 53. 



— NODOSAETA (part), Jones, Parker, and Brady, 1866, Monogr. Toram. 



Crag, Appendices, No. 57 (part), pi. i, 

 fig. 61 (not fig. 66). 



— TUBEEOSA, Brady, Parker, and Jones, 1870. Trans. Liun. Soc, 



vol. xxvii, p. 249, pi. xlii, figs. 39 a, h. 



— — Basset, 1885. Ann. Soc. Sci. Char.-Inf., p. 161, fig. 60. 



— — Fornasini, 1886. Boll. Soc. Geol. Ital., vol. v, p. 204, 



No. 231. 



— DEFOEMis, Fornasini, 1890. Mem. Accad. Sci. Bologna, ser. 4, vol. x, 



p. 471, pi. o, figs. 35—37. 



— TrBEROSA, Fornasini, 1891. Foram. Plioc. Pontic. Sav. Bologna, 



pi. ii, fig. 25. 



— — De Amicis, 1895. Naturalista Siciliauo, Anu. xiv, pp. 46 



and 63. 



— DEFOKMis, Be Amicis, 1895. Ibid., pp. 47 and 63. 



Characters. — Shell elongate, subcylindrical, straight, or nearly so. Anterior 

 portion acuminate ; posterior obtuse, and rounded. Early (alternating) chambers 

 varying greatly in their proportion to the whole shell. Later (uniserial) chambers 

 two to six in number, more or less inflated. 



As explained in the " Monograph of the Genus Polymorphina,'^ 1870, p. 249, 

 there is no essential difference between d'Orbigny's Blmorphina tuherosa and his 

 symmetrical D. nodosaria. So also D. deformis (Costa) appears to differ only in 

 degree, by irregularity of growth, from D. tuherosa; and our fig. 21 of PI. VII 

 is within the varietal limits of the same species, though more even and fusiform in 

 shape. 



Taking the subcylindrical Polymo7yhince of the Crag as a group, we see that 

 PI. I, figs. 55 — 58 represent a type ; PL I, fig. 61, is a tuberose subtype ; PI. VII, 

 fig. 21, is less tuberose and more fusiform; whilst PL VII, fig. 17, is compressed 

 and almost Marginuline in growth, with an eccentric beginning and uniserial 

 upgrowth; and PL I, fig. 66, is still more compact and like a Marginulina in 

 outline. The two latter forms are described under a separate trivial name. 



A compressed form, very close to D. tuherosa, has been found in the Pliocene 

 beds at St. Erth, by Mr. Millett. 



Occurrence. — Bimorphina tuherosa is of rare occurrence both in the recent and 

 fossil condition. Living specimens have been obtained from the Mediterranean at 



30 



