64 FORAMINIFERA 



to the exterior in the compressed stellate species or of an irreg- 

 ular tubular chamber in the subcylindrical ones ; wall of loosely 

 cemented mud or sand showing little selection, the interior with 

 a thin chitinous lining ; aperture at the outer ends of the tubular 

 portions. 



Jurassic to Recent, perhaps earlier. 



Most of the species are characteristic of cool water conditions, 

 and temperature is more of a control than depth. 



The proportion of cement is small, and it is not surprising that 

 recognizable specimxcns are not common in a fossil condition. 



Genus MASONELLA H. B. Brady, 1889 



Plate 2, figure 19 



Genotype, by designation, MasoneUa planulata H. B. Brady 

 Masonella H. B. Brady, Ann. Mag. Nat. Hist., ser. 6, vol. 3, 1889, p. 295. 



Test stellate or circular, much compressed, with a large 

 central chamber with fine branching tubules, to the periphery; 

 wall finely arenaceous, thin, especially between the tubules; 

 apertures at the open ends of the tubules. 



Recent. 



There are two species known, both from the Indian Ocean. 



Genus RHABDAMMINA M. Sars, 1869 



Plate 2, figures 7-13 

 Genoholotype, Rhahdammiyia abyssorum M. Sars 



Rhahdammina M. Sars, Forh. Selsk. Christiania, 1868, p. 248 (nomen 

 nudum); in W. B. Carpenter, Ann. Mag. Nat. Hist., ser. 4, vol. 4, 

 1869, p. 288. 



Test free, either radiate, subcylindrical, or branching; wall 

 firmly cemented, usually of sand grains but occasionally with 

 sponge spicules and other foreign bodies, showing some selec- 

 tion, interior with a thin chitinous lining, cement usually 

 yellowish-brown ; open ends of the tubes serving as apertures. 



Jurassic to Recent. 



Most of the species are characteristic of cool water conditions 

 and temperature is more of a control than depth. Some of the 

 species occur in tropical waters but usually at considerable 

 depths. 



