XAUTILID^. 
95 
Horizon. Carboniferous Limestone. 
Locality. Xot recorded, but most probably Ireland. 
Eepresented in the Collection by a single example. 
Discites sulcatus^ J. de C. Sowerby, sp. 
1826. Xaiitihis siilcatm, J. de C. Sowerby, Min. Conch, yol. yi. p. 137, 
pi. dlxxi. ff. 1,2. 
1836. Xautilus sulcatus, Phillips, Geol. of Yorkshire, pt. ii. p. 233, 
pi. xxii. ff. 31, 32. 
1843. Nautilus sulcatus, Portlock, Geol. of Londonderry, p. 404. 
1844. Nautilus sulcatus, de Koninck, Descrip, des Anim. Foss, du Terr. 
Carbonifere de la Belgique, p. 545, pi. xlyii. ff. 10, a, h. 
1852. Nautilus sulcatus, Giebel, Fauna der Vorwelt, Baud hi. Abth. i. 
p. 175. 
1854. Nautilus sulcatus, Morris, Cat. British Fossils, 2nd ed. p. 309. 
1860. Discites sulcatus, Griffith, Joiun. Geol. Soc. Dublin, p. 561. 
? I860. Nautilus sulcatus, F. A. Roemer, Beitrage zur geologisch. 
Kenntn. des uordwestl. Harzgebu’ges, Abth. iy. p. 167, Tab. xxyii. 
f. 3. 
1876. Nautilus {Discites) sulcatus, Armstrong, Young, and Robertson, 
Cat. of Western Scottish Fossils, p. 59. 
1878. Nautilus sulcatus, de Koninck, Faune du Calcaire Carbonifere de 
la Belgique (Annales du Mus. Roy. d’llist. Xat. de Belgique, 
tom. ii.), p. 126, pi. xxyii. ff. 1-4. 
Sp. Char. Shell discoid, compressed, composed of two and a half 
or three whorls only just touching each other, and all exposed in a 
rather shallow umbilicus, which has a large central perforation. 
The whorl in section is broadly sagittate, the periphery yery narrow, 
concaye, and bordered by sharp keels. The sides are inflated in the 
lower two thirds, with three or four fine spiral ridges or keels upon 
the prominent part, the lower keel forming the edge of the um- 
bilicus. The upper third of the sides is diyided by a narrow ridge 
into two deep sulci, which are not quite so wide as the peripheral 
grooye. The surface of the test is coyered by yery fine lines of 
growth, which are curved sigmoidally upon the sides, and make a 
deep, backwardly directed sinus upon the periphery. 
The body-chamber occupies about half of the last whorl. 
The septa are tolerably numerous, about twenty-six in a complete 
whorl. The siphuncle is situated very near the peripheral margin. 
Kemarl's. This species is nearly allied to D. hisulcatus, de Koninck, 
but differs from that species in having less compressed, transversely 
broader whorls, more strongly marked and persistent sulci on the 
sides, and more distant septa. 
Horizon. Carboniferous Limestone. 
