Bd. 111:9) 
THE FOSSIL FOKAMINIFERA. 
5 
as much so as if they had been drawn from recent seas — others are considerably 
eroded and stained. The porcellanous Biloadince are well preserved but the Rotalines 
generally speaking have their characters more or less obscured. 
Family Miliolidæ. 
Sub-family Miliolininæ. 
Genus Biloculina d’Orbigny, (1826). 
Milioline Foraminifera with only two chambers visible e.xternall}', each successive 
segment entirely embracing the previous ones on the same side. 
Biloculina ringens, (Lamarck). 
Plate I. Figs. 5, 6, 7 and 8. 
Miliolitds ringens, Lamakck, 1804, ilu Museum, vol. V. p, 351; vol. I.K., pi. XVII. IR. i. 
Biloculina ringens, d'Orbigny, 1826, Ann. Sei. Nat. vol. VII. p. 297, No. 2. 
> » Williamson, 1858, Rec. For. Gt. Br, p. 79, PI. VI, figs. 169, 170. 
s Ï Brady. 1884. Rep. Chall. p. 142. PI. II. figs. 5, 6. 
Characters: Shell, oval or sub-spherical, ultimate chamber projecting beyond the 
penultimate all round, and having its peripheral edge more or less rounded. Aperture 
normally at one end of the last segment; shape and size of aperture variable, gener- 
ally a symmetrically curved slit with central tongue. 
The variability of B. ringens is notorious and the few specimens from the Pecten- 
conglornerate illustrate this inconstancy of character. Figs 5 and 6 show the oval 
variety with well rounded periphery of the final chamber; figs 7 and 8 show the 
more circular form with sharper edge to the last chamber and passing towards 
B. depressa, d’Orbigny. 
Biloculina ringens is cosmopolitan in recent seas and common almost every- 
where and at all depths up to 3,CXX) fathoms. It has been recorded from the Upper 
Jurassic (Karrer) and in tertiary formations generally. 
In the Pecten-congloineratc it may be said to be a common form. The specimens 
vary in size from 0.75 to 2.9 mm. 
