REPORT ON THE FORAMINIFERA. 
133 
Orbiculina drawn out at the umbilici, so as to form a subglobular, oval, or fusiform 
shell. 
Lastly, Keramosphcera, is a little globe made up of concentric layers, each layer 
composed of a large number of chamberlets, — in other words, a spherical Orbitolite. 
From end to end, from Cornuspira and Spiroloculina to Orbitolites and Alveolina, if 
not to Keramosphcera, the series is nearly unbroken. Each successive type embodies only 
a slight modification of its predecessor, either in the number of the chambers, their more 
or less symmetrical disposition, whether spiral or cyclical, or their subdivision into 
chamberlets ; but even the features selected to characterise the genera are open to 
constant variation, and the genera themselves are for the most part additionally connected 
by dimorphous forms. 
Sub-family l. Nubecularinse. 
Nubecularia, Defrance. 
Nubecularia, Defrance [1825], Blainville, .Tones and Parker, Carpenter, Karrer and Sinzow, 
Brady, Terquem, Siddall, Seguenza. 
Amorphma, Parker [I860]. 
Sagrina, pars, Brady [1879]. 
An excellent account of the genus Nubecularia is given by Dr. Carpenter in the 
Introduction to the Study of the Foraminifera, and its wide range of variation in ex- 
ternal form is well illustrated in the accompanying drawings made from recent specimens 
by Mr. George West. 
More recently Karrer and Sinzow 1 have described and figured a series of large 
thick-shelled varieties which occur in extraordinary abundance in certain Tertiary deposits 
in the south of Russia, notably in the Sarmatian Sands of Kischenew in Bessarabia ; 
and these have been recognised by Prof. Parker as identical in general characters 
with specimens in the collection of the late Sir Charles Lyell from Miocene localities 
in the south of France. 
The two memoirs referred to, with the addition of a brief notice by Jones and Parker , 2 
of a fossil species of much earlier geological age almost complete the published 
literature of the genus. The Challenger gatherings furnish two interesting modifications 
of the type, not previously recorded, but otherwise throw but little new light upon the 
group. 
Nubecularia is found living in the laminarian and littoral zones and, rarely, at greater 
depths, in the seas of tropical and to some extent of temperate latitudes. Its geological 
history dates back to the Triassic period, and it is found also in the Oolite ; but in the 
fossil condition it is best known as a constituent of some Tertiary deposits of France, 
Italy, Russia, and elsewhere. 
1 Sitzungsb. cl. Jc. Akad. Wiss. Wien , vol. lxxiv. p. 272, pi. i. 
2 Quart. Journ. Geol. Soc., vol. xvi. p. 455, pi. xx. 
(ZOOL. CHALL. EXP.— PART XXII.— 1883.) 
Y 18 
