160 



THREE CRUISES OF THE " BLAKE. 



Norway, Bear Island, and Spitzbergen, Biloculina ringens 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 formino- 

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



Fig - . 485. — Biloculina tenera. With expanded pseudopodia. 



¥• 



(Schultze.) 



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

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



Fig. 487. 2j9. 



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 



