LITUOLIDAE 107 



can only be separated from Ammocibicides by their characteristic aperture, or by an 

 examination in fluid which brings out their perforate character. In its more advanced 

 stages of growth Ammocibicides proteus continues its resemblance to Cibicides, the 

 uniserial and biserial stages bearing great resemblance to the forms which have been 

 named Dyocibicides (C. and V. 1930, SWF, p. 30), and Rectocibides (Cushman and Ponton 

 in C. 1925, etc., LFR, 1932, p. 2). Rectocibicides indeed has projecting tubular processes 

 very like the cusps on the edges oi Ammocibicides proteus , but they are distinct apertures, 

 while I can trace no openings in the cusps on Ammocibicides. 



Average specimens are about 0-5 mm. in diameter; abnormal individuals up to 

 1-5 mm. in length. 



Nearly all the specimens found preserve the flattened formation, although later 

 chambers tend to become inflated. At Sts. 386 and WS 202 a few specimens were found 

 which have grown irregularly, and with inflated chambers throughout. It is possible 

 that they may represent a distinct species, but more material is required to settle this 

 point. At present they may be regarded as abnormal growths. 



It is not surprising to find that an organism of such simple structure as Ammocibicides 

 has a long geological history. Some time ago an American correspondent, Mrs H. J. 

 Plummer of Austin, Texas, sent me some Eocene material from Lower Wilcox strata 

 at Ozark, Alabama, on which a paper has been published ("An Eocene Foraminiferal 

 Fauna of Wilcox Age from Alabama" — J. A. Cushman and G. M. Ponton in C. 1925, 

 etc., LFR, 1932, pp. 51-72, pis. vii-ix). In the material I found specimens of an 

 organism which is certainly Ammocibicides, though it does not attain the wild growth of 

 the Discovery species. As it is not described in the paper referred to, I propose, with 

 Mrs H. J. Plummer's consent, to name it after one of the authors. 



210. Ammocibicides pontoni, sp.n. (Plate IV, figs. 8-12). 



Test free, but possibly sessile in life, planoconvex, exactly resembling in its early 

 stages neat specimens of Cibicides lobatulus. Ventral side convex, exhibiting five inflated 

 chambers with depressed sutures. Dorsal side quite flat, as though adherent in life to 

 a flat surface, sutures obscure and chambers hardly discernible, though more distinct 

 when moistened. Peripheral edge acute ; aperture, when present, a curved slit with lips, 

 on the outer edge of the final chamber. Further grovith is made by the addition of one 

 or more chambers extending in a straight series from the final chamber of the early spiral 

 series, and sometimes partly embracing that chamber. I personally have not seen any 

 specimens with more than two chambers in the second series, and none resembling the 

 abnormal growths of the recent species Ammocibicides proteus. The test is thin and built 

 of fine sand grains, much larger than those used by the recent species, with an excess of 

 grey cement. Surface smooth and neatly finished, but not polished. Colour Hght grey. 



Diameter of early spiral stage about 0-4 mm. ; thickness about 0-2 mm. ; length of 

 specimen with two extended chambers 075 mm.; breadth at widest point 0-5 mm. 



14-2 



