Messrs. Foord and OCrick—On Discites Hibernicus. 253 
more pronounced at the peripheral margin, make a deep, subangular, 
backwardly-directed sinus on the periphery. 
At the commencement of the last fourth of the second whorl, 7.e., 
at about the half of the outer whorl in the specimen, a constriction 
follows the course of the lines of growth and probably marks the 
position of a former aperture; a similar but less distinct constriction 
occurs at about the end of the first fourth of the last whorl. 
A small portion of the test is wanting on the periphery near the 
aperture, and the underlying cast of the body-chamber presents 
a roughened surface, the rugosities increasing in size towards 
the centre of the peripheral area and forming interrupted, feebly- 
curved lines having their convexity forwards. Doubtless, these are 
epidermids which reproduce the surface of the mantle at this part. 
The dimensions of the specimen are as follows :— 
Diameter var 28 506 dee 72 mm, 
‘Width of umbilicus (between sutures) ate 33 3 
6 A ( ,, margins) ... about 42 i 
Greatest thickness of last whorl aie ... about 21.5 _ ,, 
Height of last whorl at greatest diameter of shell 24 os 
Width of periphery at 35 45 10 af 
iy ce commencement of last whorl 7 Dp 
The species with which the fossil just described may be compared 
are Discites discors, M‘Coy ;1 Discites discoideus, de Koninck,’ sp. ; 
and Discites compressus, J. Sowerby,’ sp. 
From Discites discors, M‘Coy, the shell under consideration differs 
in having fewer and more compressed whorls, fewer longitudinal 
lines on the sides, a sulcate periphery with longitudinal lines, and 
also in the direction of the lines of growth. 
It differs from Discites discoideus, de Koninck, sp., in being less 
compressed, in having fewer whorls, the longitudinal lines on the 
lateral area crenulated, and in having longitudinal lines on the 
periphery. 
Discites compressus, J. Sowerby, sp., has more compressed and 
more numerous whorls, a nearly smooth shell and the longitudinal 
lines on the lateral area do not reach to the end of the first whorl. 
Its umbilical margin is more angular and its periphery more concave. 
We therefore propose to regard the specimen as representing a 
new species and to call it Discites Hibernicus. Its specific characters 
may be stated as follows :— 
Discites Hibernicus, sp. nov. 
[non Nautilus Hibernicus, d’Orbigny, Pal. univ., vol. 1. pl. ci. figs. 2,3. 1847.] 
Discoid, compressed ; whorls rather more than two; the first half 
1 Nautilus (Discites) discors, F. M‘Coy, Synopsis of the characters of the Carboni- 
ferous Limestone Fossils of Ireland, 1844, p. 17, pl. ii., fig. 5. See also Nautilus 
discors (M‘Coy) L.-G. de Koninck, Faune du calcaire carbonifére de la Belgique 
(Annales du musée royal @histoire naturelle de Belgique, Paleont. ser., vol. ii.) 
part i., 1878, p. 143, pl. xxx., fig. 8. 
» Nautilus discoideus, L.-G. de Koninck, op. cit., p. 133, pl. xxv. fig. 3. 
3 Hilipsotites compressus, J. Sowerby, Min. Conch., vol. i. p. 84, pl. xxxviii., 1813. 
See also Discites eompressus, A. H. Foord, Cat. Foss. Ceph. Brit. Mus., part 2, fig. 11, 
pp- 86 and 91. Nautilus (Discites) mutabilis, M‘Uoy, op. cit. p. 18, pl. iii., fig. 7, is 
a synonym of Sowerby’s species. 
? 
