﻿VALVULINA. 



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general Rotalian aspect are sufficient for its identification. It is intermediate to V. 

 palaotroc/ius and V. bulloides, the latter species having much fewer and more globular 

 segments. 



Distribution. — In England Valvulina plicata occurs, though very rarely, in both the 

 Lower and Upper Carboniferous Limestones ; in Scotland it is much more common in 

 the Lower than in the Upper Group ; and in the Fusulina-beds of Iowa, N. A., it is found 

 associated with V. bulloides. It is not a Permian species. 



Valvulina bulloides, nov., PL IV, figs. 12 — 15. 



Characters. — Test free (or adherent 1), oblong, rounded ; composed of a few inflated 

 segments, obscurely spiral in their arrangement. Superior surface, convex ; inferior, flat 

 or slightly concave, irregular, depressed at the umbilicus. Segments sub-globular, each 

 succeeding one considerably larger than its predecessor. Diameter, to inch 

 (0-3 to 0-5 mm.). 



This little species, which is not uncommon in the Pusulina-limestones of North 

 America, bears many points of similarity to the more modern type, Globigerina. Not 

 only is the test made up in the same way of a few globose segments, somewhat rapidly 

 increasing in size, but the excavation of the inferior surface often presents a striking 

 resemblance to the umbilical vestibule of Globigerina. The superficial rugosity also 

 bears some analogy to the sandy incrustation often observable in that genus. In point 

 of fact the minute structure of the test of Valvulina bulloides is much more like that of 

 some of the Tertiary members of the genus, than those of its own geological age. Not- 

 withstanding its apparent arenaceous exterior — glistening in strong light with adherent 

 white sand grains, the basis of the test is often distinctly perforate, as may be seen in 

 the sections represented in PI. IV, figs. 14, 15, a character that has not been satisfactorily 

 demonstrated in any of its Carboniferous congeners. The aperture, which usually affords 

 a generic feature of some importance, is scarcely ever discernible externally, owing to the 

 infiltration of the test and the adhesion of particles of the matrix or of the body to which 

 the organism may have been attached whilst living ; but specimens are occasionally met 

 with which show with sufficient precision its Valvuline peculiarities. The general struc- 

 ture of the test and the arrangement of its various parts may be readily made out from 

 transparent sections. 



Distribution. — Until comparatively recently I had supposed Valvulina bulloides to be 

 confined to the Fusulina-beds of the Upper Coal-measures of North America, in which it 

 is a common form, but I have since met with it sparingly in the Calcaire de Namur of 

 Belgium and in the Fusulina-limestone of Miatschkovo, near Moscow. The Belgian 



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