XAUTILID.T. 
117 
from each obher, the last t^vo or three near the body-chamber being 
a little nearer than those immediately preceding them. The 
siphuncle is situated above the centre, or about j of the distance 
across the ventro-dorsal diameter. The whole surface of the test is 
covered with fine lines of growth, which are visible to the naked 
eye. One of the specimens in the “ Sowerby Collection ” (Xo. 43861) 
exhibits very distinct colour-markings, arranged in spots or irregular 
bands of a blackish hue. 
Bemarhs. This species difi“ers from C. canniferus, J. de C. Sow., in 
having an extra keel inside the umbilicus (cf. fig. 15, D). Closely 
allied to the present species is the Xautilus pinguis, de Koninck, next 
to be described ; in this the young shell (for about half a volution) 
is longitudinally ridged, as in some species of Disdtes, and it has also 
a row of crenulations on each keel, up to the end of the first whorl. 
Honzon. Carboniferous Limestone. 
Locality. Ireland ; one specimen (registered Xo. 50189), from Cork. 
Represented in the Collection by several examples, including the 
one figured by J. de C. Sowerby (Joe. cit.), now in the “ Sowerby 
Collection.” 
Coelonautilus pinguis, de Koninck, sp. 
1844. Nautilus pinyuis^ de Koninck, Descrip, des Anim. Fossiles dii 
Terr. Carbonifere de la Belgique, p. 551, pi. xlviii. f. 10. {Not of 
M'Coy.) 
1849. Nautilus pinguis^ d’Orbigny, Prodr. de Paleont. Stratifrr. vol. i. 
p. 111. 
1852. Nautilus pinguis, Giebel, Fauna der Vorwelt, Band iii. Abth. i. 
p. 173. 
1878. Nautilus pinguis, de Koninck, Faune du Calcaire Carbonifere de 
la Belgique (Annales du Mus. Roy. dTIist. Xat. de Belgique, 
tom. ii.), p. 136, pi. xxx. ff. 6«-c, 7 a~c. 
Sp. Char. Shell thick, discoid, composed of about two and a half 
slightly embracing volutions, all exposed in a very deep umbilicus, 
which has rather a large perforation in the centre. The first 
whorl, for about half its length, has fine longitudinal stria3 or 
ridges, one of which is continuous and forms one of the lateral 
keels. At the commencement of the second whorl the periphery 
is slightly depressed and bears on each side a double keel, which 
gradually becomes obsolete till it finally disappears completely 
upon the last whorl, near the aperture. The periphery, losing the 
keels, here becomes rounded, so that it presents in section an ellipse 
of which the two extremities of the longer axis are truncated. The 
two keels encircling the whorls are finely crenulated, at least up to 
