Foraminifera of the Gault of Folkestone, By F, Chapman. 21 
appendix nr. 
Distribution Tables of the Foraminifera from the Gault of 
Folkestone. 
In drawing up the following tables of species;from Folkestone, a few 
additional occurrences have been added to levels in which the species 
had not been discovered at the time of publishing the descriptions in 
the foregoing parts of this work. 
In addition to this, it is necessary to make some alterations in the 
determination of a few species, as follows : — 
Ophthcilmidium tumidulum Brady, Cornuspira cretacea Reuss, C. in - 
volvens Keuss, and C. foliaeea Philippi sp.* The specimens from the 
Gault which were referred to the above-named species were thought 
originally to be porcellanous in shell structure, since the test appears 
of a chalky white colour by reflected light. On submitting them, 
however, to conditions which render them translucent, they in each case 
proved to be composed of arenaceous material, the component quartz- 
grains being of excessive minuteness, averaging * * § 004 /x in diameter. 
It is this fine arenaceous structure, with its glazed external surface, 
which gives the porcellanous appearance to the specimens. Although 
in the porcellanous groups these forms have been separated into the 
four so-called species, when removed to the arenaceous group they so 
fill up gaps in a long series dominated by the same type, that they 
cannot reasonably be included under more than one specific form — that 
of Ammodiscus incertus d’Orb. sp. So much for the imperfect character 
of Rhizopodal nomenclature. 
Trochammina concava. f It is interesting to note the close relation- 
ship between T. infiata Montagu sp., var. macrescens Brady f and the 
above, as has been pointed out to me by my friend Mr. Millett. As far 
as I have noticed, the variety macrescens is nearly devoid of arenaceous 
material, and consists usually of a chitinous test. 
The specimens from the Gault of France and England which have 
been placed under Bulimina polystropha Reuss by M. Berthelin,§ and 
later by myself, || are without doubt the same form as that described by 
Dr. Egger from the Miocene of Lower Bavaria. This discrepancy has 
probably arisen from the non-agreement of the original figure and de- 
scription of Bulimina polystropha given by Reuss, the figure showing a 
smooth test, while the specimen is described as having a rough surface.** 
Frondicula'ria pinnseformis If had already been figured and described 
by Dr. Perner from the Cenomanian of Bohemia, under the name of 
* See this Journal for 1891, pp. 574 and 575, pi. ix. figs. 10-13. 
+ See this Journal for 1892, p. 327, pi. vi. figs. 14 a, b. 
J Ann. and Mag. Nat. Hist., ser. iv. vol. vi. 1870, p. 290, pi. xi. figs. 5 ci-c. 
§ Mem. Soc. Geol. France, 1880, ser. 3, vol. i. No. 5, p. 30, pi. ii. figs. 3 a, 6. 
|| See this Journal for 1892, p. 756, pi. xii. fig. 11. 
•ff Bulimina yygmxa Egger, 1857, Neues Jahrb. f. Min., p. 284, pi. xii. figs. 10, 11. 
** Yerstein. Bohm. Kreidef., pt. ii. (1845) p. 109, pi. xxiv. figs. 53 a , b. [For 
(further details on this point see Quart. Journ. Geol. Soc., vol. 1. (1894) pp. 701-2.] 
ft See this Journal for 1891, p. 156, pi. iii. figs. 9-11. 
