REPORT ON THE FOE AMINIFEE A . 
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in others it takes the form of a ring of round or oblong beads immediately encircling 
the umbilicus, whilst there are some varieties in which it has the aspect of an embossed 
star, with straight or curved tapering rays covering the septal lines to within a 
short distance of the periphery. 
The orifice, the normal form of which is a simple curved fissure, often shows traces of 
subdivision by transverse bars, approaching in character the multiple or porous aperture 
of the Polystomellce . 
The geographical distribution of Nonionina is world-wide, specimens having been 
found in every latitude and at almost every depth at which the sea-bottom has been 
explored. There is no satisfactory evidence of the existence of the genus before the 
commencement of the Tertiary epoch; 1 but it occurs in the Eocene of the Paris Basin, 
and becomes gradually commoner in succeeding formations down to recent times. 
Nonionina depressula, Walker and Jacob, sp. (PI. CIX. figs. 6, 7). 
“Nautilus spiralis utrinque subumbilicatus,” Walker and Boys, 1784, Test. Min., p. 19, pi. iii. 
fig. 68. 
Nautilus depressulus, Walker and Jacob, 1798, Adams’s Essays, Kanmacher’s Ed., p. 641, 
pi. xiv. fig. 33. 
Nonionina perforata, d’Orbigny, 1846, For. Foss. Yien., p. 110, pi. v. figs. 17, 18. 
„ granosa , Id. Ibid. p. 110, pi. v. figs. 19, 20 
,, punctata, Id. Ibid. p. Ill, pi. v. figs. 21, 22. 
,, unibilicatula , Williamson, 1858, Eec. For. Gt. Br., p. 97, pi. iv. figs. 70, 71. 
,, crassula, Id. Ibid. p. 33. 
,, asterizans, var. depressula, Parker and Jones, 1862, Introd. Foram., Appendix, 
p. 310. 
Polystomella crispa, var. ( Nonionina ) depressula, Parker and Jones, 1865, Phil. Trans., vol. civ. 
p. 403, pi. xiv. fig. 39, a.b. 
Nonionina crassula, Fiscber, 1870, Actes Soc. Linn. Bordeaux, vol. xxvii. p. 396, No. 43. 
„ granosa, Terquem, 1882, Mem. Soc. geol. France, ser. 3, vol. ii., Mem. III., p. 43, 
pi. ii. fig. 10, a.b. 
The test of Nonionina depressula is much compressed, and the peripheral edge round ; 
the umbilici are nearly flush, that is to say, they are neither much excavated nor 
umbonate, nor do they exhibit any amount of sutural limbation ; the segments are some- 
what inflated and the margin more or less lobulated ; the shell-wall is usually very thin 
and hyaline. 
As compared with the allied forms, the characters of Nonionina depressula are those 
of a starved variety, and the conditions under which it is found support this view. It 
1 Reuss, in his memoir on the Classification of the Foraminifera, states the geological range of the genus as “the 
Silurian formation (!), the Carboniferous Limestone, and from the Chalk forwards ” (Sitzungsb. d. k. Ah. JViss. 
Wien, 1861, vol. xliv. p. 389). The first of these is quoted interrogatively, and may be dismissed as wanting 
confirmation. The Carboniferous specimens referred to are almost certainly forms now assigned to the genus Endotliym ; 
and those from the Chalk are probably Pullenice which were included by d’Orbigny, and at that time by Reuss also, in 
the genus Nonionina. 
(ZOOL. CHALL. EXP. — PART XXII. — 1884.) 
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