REPORT ON THE FORAMINIEERA. 
139 
Biloculina, d’Orbigny. 
Miliolites, pars, Lamarck [1804]. 
Larjenula, pars, Fleming [1822], 
Miliola, pars, Defrance [1824], Blainville. 
Pyrrjo , Defrance [1824], Blainville. 
Biloculina, d’Orbigny [1826], Reuss, Bornemann, Costa, Parker and Jones, Williamson, Terquem, 
Karrer, Carpenter, Seguenza, Brady, Schwager, Schulze, &c. 
Renoidea , Brown [1827]. 
Nurnmidina, Macgillivray [1843], Tliorpe. 
I 
The genus Biloculina requires no minute description. It may be said to comprise 
just those Milioline Foraminifera which have only two chambers visible externally, each 
successive segment entirely embracing the previous ones on the same side; and although the 
Biloculine form of shell merges by insensible degrees through such varieties as Biloculina 
tubulosa, Costa, Biloculina lucernula, Schwager, Triloculina cuneata, Karrer (the Bilocu- 
line form of which is shown in PI. I. figs. 19, 20), and others, into the Triloculine condition, 
the typical arrangement of the segments is less liable to variation than that of the allied 
groups of Miliola. 
The geographical distribution of the genus is world-wide, and its bathymetrical 
range includes every depth from the rock-pools of the littoral zone down to 3000 
fathoms. 
Perhaps the most noteworthy fact in connection with the occurrence of the Biloculine 
type is that brought into notice by Prof. G. O. Sars, of Christiania, in his official 
report on the Norwegian sea-fisheries for the year 1876, 1 in which he gives a short 
account of the biological conditions of the “ deep-water cold area ” of the northern part of 
the North Atlantic. The area so designated occupies a considerable portion of the region 
between Norway, Bear Island, and Spitzbergen on one side, and the Faroe Islands, Iceland, 
and Greenland on the other. It has a tolerably uniform bottom temperature of from 0°to 
1 0, 6 C. (32° to 34° - 9 Fahr.), and the depth ranges from 300 to 2000 fathoms. The 
sea-becl, especially of the deeper portions of the area, consists of a soft, light-coloured, 
sticky mud, of which the most important organic constituent is the porcellanous 
foraminifer, Biloculina ringens. This deposit has been named “ Biloculina clay,” but 
the term is not to be understood in quite the same sense as that in which the words 
“ Globigerina ooze ” or “ Badiolarian ooze ” are employed ; for although of the microzoa 
present, by far the most conspicuous are Biloculina, the entire number of specimens of 
that genus is stated not to amount to more than two per cubic centimetre. 2 Neverthe- 
less, the deposit has certain well-marked peculiarities, and the following results of the 
1 Indberetninger til Departementet for det Indre fra Professor Dr. G. O. Sars om de af ham i Aarene, 1864-1878, 
anstillede Unders0gelser angaaende Saltwandsfiskerierne. Christiania, 1879. 
2 Vide Schmelk, on Oceanic Deposits, Norwegian North Atlantic Expedition, 1876-1878, pt. ix., Chemistry, p. 49 
et seep 
