174 THE FOEAMINIFERA 



present day, and is but rarely found in depths greater 

 than 900 or 1,000 fathoms. (Plate 9, tig. Q.) 



Genus Miniosina, Millett. 



Test typically spiral, conical, or trochoid ; cham- 

 bers having a biserial or triserial arrangement. 

 Aperture complex, consisting of two distinct orifices, 

 one of them usually being a slit at the base of the 

 inner wall of the final chamber, the other an opening 

 varying in shape and situated near the apex of the 

 chamber ; the two orifices frequently connected 

 internally by means of a bent tube or septum. Shell- 

 wall cellular or spongy. Becent. 



Example. — M. Jiystrix, Millett, ' Journ. Koy. Micr. 

 Soc' 1900, p. 549, pi. iv. fig. 14. 



The test of this species is triserial in the earlier 

 part, afterwards becoming biserial. Double apertures, 

 oval, with a bordered margin. Chambers armed each 

 with a spine at the salient margin. Mr. Millett 

 found this species in abundance in the Malay Archi- 

 pelago. Rece/it. (Plate 9, fig. E.) 



Genus Pleurostomella, Keuss. 



Test biserial ; aperture large, usually arched or 

 semicircular, with a notch at the middle of the lower 

 edge, situated at the top of the nearly erect septal 

 face of the last segment. Cretaceuas. Recent. 



Example. — P. siibnodosa, Eeuss, ' Sitzungsb. d. k. 

 Ak. Wiss. Wien,' vol. xl. 1860, p. 204, pi. viii. 

 figs. 2rt, h. 



The features of this species are the cylindrical 



