196 
THE VOYAGE OF H.M.S. CHALLENGER. 
Planispirina communis, Seguenza (PI. CXIV. figs. 4-7). 
Planispirina communis, Seguenza, 1879, Atti. R. Accad. dei Lincei, ser. 3, vol. vi. p. 310, 
pi. xvii. fig. 18, 18a. 
The drawings of Planispirina communis accompanying the original notice of the 
species are altogether insufficient to illustrate the variety of external contour which it 
assumes, but by the help of specimens kindly furnished by the author I have been 
enabled to identify a number of examples amongst the recent Foraminifera collected by 
the late Mr. Waller, at present in the possession of the Rev. A. M. Norman. From some 
of these, which had been previously set aside for independent description, the figures 
in PL CXIV. have been drawn. 
The test of Planispirina communis is less regular than that of Planispirina 
contraria; it is seldom equally convex on the two faces, and occasionally almost flat 
on one side ; and the peripheral margin of the spiral portion often tapers to a sharp 
edge. The later chambers of the adult shell generally exhibit a change from the spiral 
to a rectilinear mode of growth, in consequence of which the test presents a more or less 
elongate or crosier-like contour. This character, and the Nummuline lamination of the 
walls, which is well seen in abraded specimens, constitute its most conspicuous features. 
The recent examples above referred to were dredged off the Faroe Islands, at a depth 
of 170 fathoms, and the species has not, so far as I am aware, been found elsewhere in the 
living condition. 
The fossils which form the subject of Prof. Seguenza’ s description were from the 
deeper Pliocene deposits of Messina, in which they are stated to occur in tolerable 
abundance. 
Planispirina exigua, H. B. Brady (PI. XII. figs. 1-4 ; Woodcut, fig. 5, b.). 
Hauerina exigua, Brady, 1879, Quart. Journ. Micr. Sci., vol. xix., N. S., p. 53. 
Test free, thin, discoidal, planospiral ; composed of a number of convolutions of a 
narrow, slightly embracing tube. Convolutions five to eight in number ; the earlier 
whorls non-septate, as in Cornuspira ; those subsequently formed each divided into two 
or three segments ; the spiral suture and septa alike obscured externally by the alar 
extensions of the investing wall over the lateral surfaces of the shell. Aperture a simple 
terminal slit. Diameter, ^th inch (0*5 mm.) or less. 
This inconspicuous little shell is common in the shallow-water sands of the tropics, 
and is occasionally found at greater depths amongst coral-debris. The record of its 
occurrence extends to nineteen localities, of which fourteen are at depths of less than 25 
fathoms, the remainder ranging; from 100 to 620 fathoms 1 . 
