﻿ENDOTHYRA. 



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Endothyra crassa, Brady, PI. V, figs. 15 — 17. 



Involutina crassa, Brady, 1869. Report Brit. Assoc., Exeter MeetiDg, pp. 379, 382. 



Characters. — Test free, spiral, nautiloid, subglobular, slightly compressed laterally, 

 nearly symmetrical ; composed of several convolutions, of which the latest encloses all the 

 earlier ones. Segments numerous, about ten in each convolution, broad, convex, embracing. 

 Septa marked externally by slightly depressed lines. Texture distinctly arenaceous. 

 Surface smooth except around the umbilicus. Diameter, inch (1*2 mm.). 



For the nearest isomorph of this species we must turn to the genus Nonionina, and in 

 the small thick subglobular varieties, such as N. umbilicatula and N. pompilioides, we may 

 find almost exact morphological parallels. Endothyra crassa is, however, a somewhat larger 

 organism than the corresponding modification of the Nonionine type, and the test is 

 unmistakeably arenaceous in its minute structure. The surface generally is very nearly 

 smooth, but near the umbilicus it is more or less rugose and granular, sometimes studded 

 with little tubercles. But few of the specimens are perfect, the terminal segment being 

 often incomplete or broken. Amongst the Endothyra its nearest ally is E. globulus, but 

 the smaller size and compressed form of the latter are sufficiently distinctive. The only 

 Carboniferous Foraminifer likely to be confounded with E. crassa is Lituola Bennieana, 

 a fossil of still larger dimensions, with fewer and more ventricose segments, and labyrinthic 

 interior (see PI. I, figs. 8 — 11). The three drawings, PI. V, figs. 15 — 17, are from 

 different individuals, all collected by Dr. Harvey B. Holl at Great Ormes Head. 



Distribution. — Endothyra crassa is nowhere very common. In England and Wales it 

 has only been found in the Lower Carboniferous Limestones ; in Scotland only in the 

 Lower Carboniferous Limestone Group. The finest set of specimens I have seen 

 was collected from the Mount Lothian Quarry, Edinburghshire. In Belgium one or two 

 specimens have been met with in the Calcaire de Vise. Similarly rare examples have 

 been observed in the Fusulina-limestones of Russia. 



Endothyra radiata, Brady. PI. V, figs. 10 — 12. 



Involutina radiata, Brady, 1869. Report Brit. Assoc., Exeter Meeting, pp. 379, 



382, &c. 



— — Id., 1871. (In Young and Armstrong's Catal.) Trans. Geol. 



Soc. Glasgow, vol. iii, Suppl., p. 14. 

 Endothyra — Id., 1873. Ibid., vol. iv, pt. iii, p. 271. 



— — Id., 1873. Mem. Geol. Survey Scotland; Expl. Sheet 23, pp. 



63, 95, &c. 



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