160 THREE CRUISES OF THE “BLAKE.” 
Norway, Bear Island, and Spitzbergen, Biloculina ringens forms 
the most important organic constituent of the bottom deposits, 
and Pourtalés and Sars have named this the Biloculina clay ; 
but this term is hardly to be understood in the same sense in 
which we speak of globigerina ooze, the Biloculine forming 
but a very small proportion of the ooze deposit. (Fig. 485.) 
Fig. 485. — Biloculina tenera. With expanded pseudopodia. TP. (Schultze.) 
Orbiculina adunca (Fig. 486) is a very common deep-water 
form ; it attains a diameter of 6 mm. In both Orbiculina and 
Orbiculina adunca. (Brady.) 
its ally, Orbitolites, the young of the disk-like foraminifer is 
nautiloid (Fig. 487); but as the chambers of the adult increase 
