﻿114 CARBONIFEROUS AND PERMIAN EORAMINIFERA. 



free Nodosariform group, such specimens as those which have been described have a 

 much nearer relationship to the adherent forms which constitute the genus Stacheia. 

 There may at times be some difficulty in recognising them by external characters, but 

 the differences in minute structure supply a certain means of distinction. 



Distribution. — In England Stacheia marginulinoides has been only found in the 

 higher beds of the Carboniferous Limestone, and it is by no means common. In 

 Scotland I have note of its occurrence in but two localities, both in the Lower Car- 

 boniferous Limestone Group. 



Stacheia fusiformis, nov. PI. VIII, figs. 12 — 16. 



Characters. — Test adherent, short, stout, rounded, tapering at both ends ; com- 

 posed of layers of chamberlets (or subdivided segments) more or less regularly and 

 symmetrically disposed round a thin columnar foreign body, each layer embracing the 

 previous one except at its peripheral margin. Test sometimes marked with slight 

 transverse constrictions over the sutural lines. Surface granular or nearly smooth. 

 Length inch (0'6 mm.). 



As usually found, growing round a straight axis, Stacheia fusiformis is a nearly sym- 

 metrical body, not unlike the Nodosarine genus Glandulina in general external aspect. It 

 is broader at the centre, and relatively shorter than other varieties of the type ; circular in 

 transverse section, and almost devoid of those depressions, excavated lines, or other super- 

 ficial markings which in most Foraminifera serve to indicate to a greater or less extent the 

 structure of the interior. The chambers are very numerous, very thin and regular, and 

 are subdivided into minute chamberlets. The transverse secondary septa are thinner 

 than the proper chamber-wall, and apparently subordinate in importance to it, as shown 

 in PI. VIII, fig. 16. In most of the sections that have been made, in which the 

 specimens are well enough preserved to exhibit anything of internal structure, the 

 remains of the central column can still be traced. Altogether Stacheia fusiformis is very 

 closely related to S. marginulinoides, and what has been written of the structural relations 

 of the latter species is in general terms true of the former. 



Distribution. — In England Stacheia fusiformis is found in both the higher and lower 

 divisions of the Carboniferous Limestone Series ; in Scotland it is present in both the 

 Lower and Upper Carboniferous Limestone Group, but the condition of the specimens 

 from the latter renders them difficult of recognition. 



