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Show 1894.] FORAMINIFERA F R O M TRINIDAD. 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: - Frondicularia (including Flabellina). Cristellaria. Nodosaria. Sayrina. Uvigerina. Lagena. Polymorphina. Primordial Form. This, of course, represents the development of the Nodosarian and Frondicularian series only. The biserial and triserial structure of the Textularians, Bulimines, &c. suggests that their development has lain through Polymorphina also. The Globigerine, Botaline, and Milioline series may have risen from the same primordial form; but in these the course of development was different. § 3. Descriptions of new Forms of Foraminifera. 1. STILOSTOMELLA RUGOSA, nov. gen. et sp. (Plate XLI. figs. 10, 11.) Test usually consisting of 3-4 (but occasionally more) nodosari-forrn 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'Orbio'ny's model of Nodosaria radicula given by Parker, Jones, and Brady in Ann. & Mag. Nat. Hist. ser. 3, xvi. 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 |
