REPORT ON THE PORAMINIFERA. 
371 
Bigenerina robusta, H. B. Brady (PL XLY. figs. 9-16). 
Bigenerina robusta, Brady, 1881, Quart. Journ. Micr. Sci., vol. xxi., N. S., p. 53. 
Test elongate, sub cylindrical : early portion compressed, and tapering to a blunt point, 
composed of a number of segments arranged, as in Textularia, in two more or less regular 
alternating series : later portion cylindrical, convex or truncate at the distal end ; con- 
sisting of numerous very short segments, tbe marginal outline of which is often ventricose 
and irregular. Aperture in the early stage Textularian in form and position ; in adult 
specimens terminal and porous. Length, -jtth inch (4‘2 mm.), sometimes more. 
In certain localities where arenaceous Textulcirice are abundant and grow to a large 
size, the specimens are apt to assume considerable diversity of form. Some of them, 
perhaps the largest number, are tolerably regular in contour and mode of growth ; others, 
though irregular, complete their tests in the normal biserial manner ; whilst the rest 
become dimorphous, and put on a number of uniserial segments. In rare instances, the 
tests, which retain their Textularian character to maturity, exhibit a porous aperture 
(PI. XLIII. fig. 3), but in the dimorphous or Bigenerine condition the multiple orifice is 
an almost invariable feature, the only exceptions being those in which the pores have 
coalesced so as to form a single irregular opening. In view of these facts, it is probable 
that, notwithstanding the strikingly distinct appearance of Bigenerina robusta, it may 
represent nothing more than a local dimorphous variety of Textularia agglutinans. 
Monstrous specimens, in which the organism has divided at an early stage, or otherwise 
given rise to two or three cohering individuals are not uncommon, and they serve to show 
how little value is to be attached to the form of the aperture as a zoological character. 
Examples of this sort are represented in PI. XLY. figs. 15 and 16, the former of 
which is a double shell, one individual having a Textularian the other a porous aperture ; 
whilst the latter consists of three tests united at the base, one of them still in the 
Textularian stage, another with an irregular central orifice, and the third in the more 
common condition, with a number of pores near the middle of the final segment. 
One of the most interesting points in connection with this species is its close 
resemblance to certain Carboniferous fossils, described several years ago under the name 
Climacammina antiqua . 1 The affinity of these fossils to the genus Bigenerina was 
to some extent recognised, and the term Climacammina was introduced provisionally, 
1 Monograph of Carboniferous and Permian Foraminifera, p. 68, pi. ii. figs. 1-9, and on a later page a more 
regular specimen of the same species appears under the name Bigenerina patula, p. 136, pi. viii. figs. 10, 11, and pi. x. 
figs. 30, 31. 
Since the publication of the Monograph, the same forms have been described by von Moller, under the names 
Cribrostomum pyriforme, Cribrostomum patulum, &c., Mdm. de VAcad. Imp. Sci. St.-Pdtersbourg, ser. 7, vol. xxvii. No. 5, 
pp. 57, 65, &c. 
Should further research show, as I believe it will, that the palaeozoic and recent specimens belong zoologically to 
identical species, the name Bigenerina patula would take precedence of Bigenerina robusta. 
