160 



THREE CRUISES OF THE " BLAKE. 



Norway, Bear Island, and Spitzbergen, BUoculina 7'ingens forms 

 the most important organic constituent of the bottom deposits, 

 and Pourtales 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 Biloculinse forming 

 but a very small proportion of the ooze deposit. (Fig. 485.) 



Fig. 485. — Biloculina tenera. With expanded pseudopodia \^. (Schultze.) 



Orhiculina adunca (Fig. 486) is a very common deep-water 

 form ; it attains a diameter of 6 mm. In both Orbiculina and 



Fig. 486. \o. 



Fig. 487. \o. 



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 



