﻿64 



CARBONIFEROUS AND PERMIAN FORAMINIFERA. 



Spirolina nautiloides, d'Orbigny, 1826. Ann. Sci. Nat., vol. vii, p. 287, No. G. 

 Lituola natjtiloidea, d'Orbigny, 1840. Mem. Soc. Geol. Fr., vol. iv, No. 1, p. 29, 



pi. ii, figs. 28—31. 



— — Id., 1846. For. Toss. Vienne, p. 138, pi. xxi, figs. 20, 21. 



— — Farlcer and Jones, 1860. Ann. and Mag. Nat. Hist., ser. 3, 



vol. v, p. 287. 



— — Reuss, 1860. Sitzungsb. k. Akad. AViss. Wien., vol. xl, p. 220,. 



pi. x, figs. 5 — 8. 



— — Carpenter, 1862. Introd., p. 144, pi. Ti, fig. 44. 



Characters. — Test free, elongate, compressed, crozier-shaped, rounded at the base,, 

 truncate or convex at the apex, margin rounded. Early chambers convoluted, later ones 

 in straight series. Segments numerous, narrow. Aperture labyrinthic, or consisting of 

 numerous, irregular orifices. Length y- - inch (2'5 mm.). 



What has already been said in the general description of the genus leaves little 

 beyond matters of detail to be noticed concerning this its central type. 



The dimensions of Lituola nautiJoidea above given refer only to the Carboniferous 

 specimens — it is in the microzoic rocks of Cretaceous age that the species appears to 

 greatest advantage. According to d'Orbigny it attains the length of 7 millim. or more 

 than a quarter of an inch in the White Chalk of the Paris basin, and Professor Reuss 

 records even larger dimensions, viz. 9 - 87 mm., or nearly four tenths of an inch, in. 

 specimens from the Chalk of Westphalia. Not only does the species vary in size, but 

 also in many other external features, such as the condition of the surface as to rugosity, 

 the relative development of the spiral and straight portions of the test, and the convexity 

 of the segments. It is necessary to bear these facts in mind in judging of specimens — 

 few in number, and worn and obscure in their characters — as they appear in the Carbo- 

 niferous beds, yet such forms as that represented in the plate are but little removed 

 in morphological characters from some of those of Cretaceous origin figured by Professor 

 Reuss. 



Distribution. — Very rare ; only known as a Carboniferous species by one or two speci- 

 mens found in the Bottom Limestone at Skelly Gate, near Ridsdale, Northumberland. 



Lituola Bennieana, nov,, PI. I, figs. S — 11. 



Characters. — Test free, nautiloid, subglobular, somewhat depressed at the umbilicus ; 

 margin rounded. Segments few in number, about five visible externally, inflated. 

 Aperture compound, consisting of several orifices of various sizes, distributed irregularly 

 over the face of the terminal segment. Interior labyrinthic. Diameter yg- inch (2*5 mm.) 

 or more, thickness y^- inch (2'0 mm.). 



