1894.] 



rORAMINIFERA TROM TRITflDAD. 



649 



what may be called the embryonic development is hidden and 

 masked within so small a space (generally a mere lump or boss) 

 that its details cannot be made out. But here and there a specimen 

 delays, as it were, the development of its mature form beyond the 

 usual period, and enables us to catch a glimpse of the genealogy of 

 the type. What I have endeavoured to express and explain in the 

 preceding remarks may be represented in a tabular form as 

 follows : — 



Frondicnlaria 

 (inchiding Fhihellina). 



Cristellaria. 



Nodosaria. 



Sagrina. 



Uvigerina. 



Lagena. 



Polymorphina. 



Primordial Form. 



This, o£ course, represents the development of the Nodosarian 

 and Frondicularian series only. The biserial and triserial structure 

 of the Textularians, Bulimines, &c. suggests that their develop- 

 ment has lain through PoJymorplmia also. The Globigerine, 

 Eotaline, and Milioline series may have risen from the same 

 primordial form ; but in these the course of development was 

 different. 



§ 3. Descriptions of neiv Forms of Foraminifera. 



1. Stilostomella etjgosa, nov. gen. et sp. (Plate XLI. 

 figs. 10, 11.) 



Test usually consisting of 3-4 (but occasionally more) nodosari- 

 form chambers, rather rapidly increasing. The axis is generally 

 slightly arcuate. Texture rough. Aperture crescentic, often 

 situated in a produced neck. Internally the aperture is furnished 

 with a hollow conical process, shaped somewhat like a shoe-horn, 

 the open side of the process being on the inner side of the 

 crescentic aperture. 



The shape of the shell is fairly represented by the figure of 

 D'Orbigny's model of Nodosaria radicula given by Parker, Jones, 

 and Brady in Ann. & Mag. Nat. Hist. ser. 3, ivi. 1865, pi. i. fig. 27. 

 The last chamber is, however, often more produced and terminates 

 in a neck, at the end of which is the aperture. The texture of the 

 shell is apparently of the character of that of Lagena aspera, or of 



