EEPOET ON THE FOEAMINIFEEA. 
411 
Kar Nicobar and the same author in his recent scheme of classification has remitted the 
type to what is evidently its natural position, placing it in the same group with 
Bulimina and Virgulina. 2 
In its fully developed condition the test of Pleurostomella is biserial and Textularian ; 
in the exceptional cases in which it is uniserial, the later segments are obliquely set and 
alternating. The septal face is oblique or nearly vertical, and is directed alternately 
towards the two peripheral edges of the test. The aperture is situated on the septal face 
of the terminal segment, close to the distal extremity, usually in a slight depression. It 
is subject to a good deal of variation in point of form, but in typical specimens consists 
of a dome-shaped or semicircular orifice, with a vertical notch or slit at the middle of the 
inferior edge. In some shells the notch is wanting, in others the aperture has the 
appearance of a T-shaped fissure, whilst in others again, it takes the shape of a 
symmetrical three- or four-lobed opening. 
The geographical distribution of Pleurostomella as a recent genus, so far as at present 
known, is limited to one or two localities in the South Pacific and South Atlantic. As a 
fossil it has been found in various portions of the Cretaceous system of Bohemia and 
North Germany (Reuss, Marsson), England (Moore), Ireland (Wright), and France 
(Berthelin); in the earlier Tertiary formations of South Germany (Gtimbel), and Hungary 
(Hantken) ; and in the later Tertiary deposits of the Nicobar Islands (Schwager), and 
Central Italy (Terrigi). 
Pleurostomella brevis, Schwager (PI. LI. fig. 20, a. b.). 
Pleurostomella brevis, Schwager, 1866, Novara-Exped., geol. Theil, vol ii. p. 239, pi. vi. fig. 81. 
The original figures of this species represent a somewhat compressed, ovate test, with 
comparatively few segments and rounded base. The specimen portrayed in PI. LI. 
fig. 20, a.b., is of similar contour, but has even fewer segments. 
This variety occurs with other Pleurostomellce off the Ki Islands, Indian Archipelago, 
129 fathoms. 
Dr. Schwager’s fossil specimens were from the rich Pliocene deposits of the Nicobar 
Islands. 
Pleurostomella ra.pa, Gtimbel (PI. LI. fig. 21, a.b.). 
Pleurostomella rapa, Gtimbel, 1868, Abh. d. k. bayer. Ak. Wiss.,II. Cl., vol. x. p. 630, pi. i. fig. 54. 
The figured specimen answers pretty closely to Gtimbel’s description of this species ; 
but unfortunately his drawing ( loc . cit.) only gives one aspect of the shell, and is on too 
small a scale to be of much assistance as to minute . characters. The test is short, very 
broad at the distal end, and tapers rapidly to a point at the initial extremity ; the 
1 Novara-Exped., geol. Theil, vol. ii. pi. vi. figs. 79-81. 2 Bollet. del B. Com. Geol., 1876-1877. 
