﻿136 CARBONIFEROUS AND PERMIAN FORAMINIEERA. 



laria, with not less than forty chambers. No zoological description is given of the 

 species, the dimensions of the specimens are not stated, nor is there any record of the 

 magnifying power employed for the figures. The drawings which have been accurately 

 copied (PI. X, fig. 23, a, b) represent a very long, narrow, compressed shell, slightly 

 irregular and curved in outline, and with even margin ; the septa marked by fine lines 

 without constriction or superficial depression ; the segments regular and very numerous. 

 To these particulars which are based upon Dr. von Reuss's figures I can add nothing. 

 Distribution. — Lower Zechstein of Gera in Thuringia. 



D 



Subgenus. — Bigenerina, d ' Orbigny. 

 Bigenerina, d'Orbigny, Parker and Jones, Carpenter, Seguenza, Brady, Schwager. 



General Characters. — Test free, regular, elongate ; formed of numerous segments ; 

 the earlier ones arranged in two alternate parallel series ; the later ones in a single 

 straight or curved line. Aperture simple or labyrinthic. Surface, rough. 



In strict zoological sense Bigenerina is but a subordinate group of the genus 

 Textularia, characterised by a dimorphous habit of growth. The earlier chambers are 

 arranged on the typical biserial plan, whilst the later ones are joined end to end in a single 

 row. Such forms are more common in the recent condition than as fossils ; they are 

 generally of small size and of long attenuated contour, the Textularian segments 

 occupying but a small part of the whole shell. A limited number of specimens pertain- 

 ing to this sub-type have been found in material of Carboniferous age, and these belong 

 to a short stout variety not hitherto described. 



Bigenerina patula, nov. PI. VIII. figs. 10, 11, and PI. X, figs. 30, 31. 



Characters. — Test oblong, rounded, subcylindrical ; somewhat compressed and 

 tapering in the earlier portion. Biserial segments, numerous, broad, ventricose ; 

 uniserial segments few in number, rounded. Aperture, either a large single central 

 orifice, or compound and labyrinthic. Length, inch (125 mm.). 



This short broad variety of Bigenerina seldom shows more than two or three 

 uniserial chambers and therein differs conspicuously from such forms as Bigenerina 

 nodosaria and B. digitata, the biserial segments of which often constitute so small a 

 proportion of the whole shell as to be recognised with difficulty. It is essentially a 



