608 
THE VOYAGE OF H.M.S. CHALLENGER 
The characters of the genus Orbulina are best studied in connection with the typical 
species Orbulina universa, from which the varietal modifications differ only in super- 
ficial ornament and similar minor details. Of the close relationship that exists between 
Orbulina and Globigerina there can be no doubt, and by some writers the former is treated 
as a subgeneric section of the latter genus. I was at first disposed to accept this view. 
It involves the supposition that the internal polythalamous shell is an actual Globigerina, 
of which the visible spherical chamber is the final segment. Morphologically speaking 
there is nothing unreasonable in such an explanation ; at the same time, the adult test 
has characters as well marked and as constant as those which are employed to distinguish 
many other genera of Foraminifera, and it appears on the whole advantageous to recognise 
both generic terms. 
The limits of the distribution of the genus, whether geographical or geological, are 
those of the typical species, Orbulina universa. 
Orbulina universa, d’Orbigny (PI. LXXVIII.; PI. LXXXI. figs. 8-26; 
PL LXXXII. fig. 1-3). 
* l Polymorpha Sphcerulce vitrece,” Soldani, 1791, Testaceograpliia, vol. i. pt. 2, p. 116, pi. cxix. 
figs. I.-N. 
Orbulina universa, d’Orbigny, 1839, Foram. Cuba, p. 3, pi. i. fig. 1. 
„ „ Id. 1839, Foram. Canaries, p. 122, pi. i. fig. 1. 
Miliola ( Monocystis ) arcella, Ebrenberg, 1854, Mikrogeologie, pi. xxx. fig. 1. 
„ sphcerula, Id. Ibid. pi. xxxi. fig. 1, a.b.c. 
Orbulina granulata, var. atra, Costa, 1856, Atti dell’ Accad. Pont., vol. vii. p. 116, pi. xi. fig. 2. 
„ var. areolata, Id. Ibid. p. 117, pL xi. fig. 4. 
„ universa. Id. Ibid. p. 114, pi. xi. fig. 5. 
„ %. Williamson, 1858, Eec. For. Gt. Br., p. 2, pi. i. fig. 4. 
„ punctata, Terquem, 1862, Foram. du Lias, 2 ifeme mem., p. 432, pi. v. fig. 5. 
Globigerina ( Orbulina ) universa, Owen, 1867, Journ. Linn. Soc. Loud., vol. ix., Zool., p. 149, 
pi. v. fig. 1. 
„ continens, Id. Ibid. figs. 3, 4. 
„ „ acerosa, Id. Ibid. fig. 2. 
,, „ universa, Brady, 1859, Quart Journ Micr. Sci., vol. xix., N. S., p. 75. 
Double specimens (PL LXXXI. figs. 20, 21 ; Pl. LXXXII. figs. 2, 3). 
Globigerina bilobata, d’Orbigny, 1846, For. Foss. Vien., p. 164, pl. ix. figs. 11-14. 
Orbulina granulata, var. impressa, Costa, 1856, Atti dell’ Accad. Pont., vol. vii. p. 117, pl. xi. 
fig. 4. 
Globigerina bipartita, Eeuss, 1863, Bull. Acad. Eoy. Belg., ser. 2, vol. xv. p. 156, pl. iii. 
fig. 46. 
„ ovoidea, Seguenza, 1880, Mem. E. Accad. dei Lincei, ser. 3, vol. vi. p. 228, pl. xvii. 
fig. 39. 
Orbulina universa is one of the commonest of pelagic Foraminifera. This fact has 
only been generally recognised of late years, and the earlier descriptions of the species 
