94 CARBONIFEROUS AND PERMIAN FORAMINIFERA. 



found in British fossiliferous limestones, being one twentieth of an inch or more in long 

 diameter when fully grown. The test is commonly thicker, and the septation in conse- 

 quence often obscure; for the same reason they likewise present greater variation in 

 external aspect and condition than those of less vigorous habit. British specimens, on 

 the other hand, rarely exceed one thirty-fifth of an inch in diameter, and the chambers 

 are rather more inflated and distinct. Their hue is darker, but this is due to the colour 

 imparted by the shaley or marly material in which they are usually embedded. 



The foregoing characters are sufficient to distinguish typical examples of Endothyra 

 Boiomani, and the departures from them in minor particulars are easily recognised. 

 Some of the thick-shelled examples have little or no depression at the umbilicus, and the 

 margin of the test has no sharp constrictions. Others become bi-convex, have a rounded 

 periphery and nearly even margin, the septa being only distinguished by slightly 

 depressed lines, thus approaching E. globulus in general form ; the latter, however, may 

 always be recognised by its long narrow embracing chambers, and its more delicate 

 proportions. 



Distribution. Of all the Endothyra, probably E. Bowmani is the most widely 

 diffused. In the Lower and Upper Limestones of England and Wales, and in the Lower 

 and Upper Carboniferous Limestone Groups of Scotland it is alike common, and in 

 Ireland it is not wanting. Sections of the Fusulina-rocks of the Caucasus attest its 

 presence ; and, as has been above noted, one of the limestone beds of Sub-carboniferous 

 age in Indiana is almost entirely composed of its remains. 



ENDOTHYRA AMMONOIDES, Brady. PI. V, figs. 5, 6. 



ENDOTHYRA AMMONOIDES, Brady, 1873. Mem. Geol. Survey Scotland ; Expl. Sheet 



23, pp. 63, 95, &c. 



Characters. Test free, discoidal, complanate or slightly biconcave, nearly symmetrical 

 bilaterally ; composed of several (8, 10, or more) convolutions of a spiral line of chambers 

 in one plane. Convolutions narrow, increasing gradually in width; regular, slightly 

 embracing. Segments very numerous, somewhat oblique. Septa, marked in young 

 shells by slightly excavated lines, and in larger specimens by conspicuous, broad, more or 

 less limbate bands. Periphery rounded. Surface granular. Aperture small, distinct. 

 Diameter -$ inch (0'5 mm.). 



A very pretty and distinct little species, not without some resemblance at first sight 

 to the feeble recent varieties of the genus Operculina. In small specimens of Endothyra 

 ammonoides the sutures are somewhat depressed, and the periphery is correspondingly 

 constricted at each septum, but in larger ones the depressions are filled in by bands of 



