166 



THREE CRUISES OF THE " BLAKE. 



Fig. 504. 



One of the most variable foraminifers is Nodosaria radicula 



(Fig. 504), an Atlantic species of wide distribution. 



It is known by innumerable specific names, and 

 the list of its varieties, as given by Dr. 

 Goes, fills no less than ten quarto pages, 

 these varieties representing all those 

 possible combinations of smoothness, 

 roughness, and striation of the test, or 

 in the shape of the chambers, which Nodosaria 

 seemed important to their describers. dlcvla - y- 

 In many other species, also, names have 

 been multiplied indefinitely. A species widely 

 spread, both over the coralline bot- 

 tom and ooze, is Nodosaria com- 

 munis (Fig. 505), which attains a 

 size of 22 mm. It closely resem- 

 bles one of the cretaceous species, 

 and dates back to the permian. 

 From the same bottom comes the 

 diminutive Cristellaria erepidida 

 (Fig. 506), remarkable for its beau- 

 tiful pearly shell. The West Indian 

 specimens of Cristellaria calcar 

 (Fig. 507) fully equal in size those Fig . soa^Cmtei- 



f rom the chalk and tertiaries. laria ■ <*epiduia. 



Closely allied to the Nodosarinse is Sagrina x ' 



dimorpha (Figs. 508, 508 a), abundant in the ooze. It attains 



Fig. 505. 

 Nodosaria 

 communis, 

 f (Goes.) 



a size of 4 mm. in length. Living specimens of Polijmorphina 

 ovata (Fig. 509) have been obtained by the " Blake " and 

 " Challenger " in the Caribbean district. 



