NArTILIDiE. 
93 
of wbolis &c. — are those of M‘Coy’s species, and, moreover, there is 
no other species with which Sowerby’s form could be confounded. 
Sowerby’s description runs thus : — “ Shell Hat, smooth ; margin 
broad, Hat, perpendicular to the sides ; volutions four or five, almost 
wholly exposed ; aperture oblong rectangular.” 
To this he adds the following : — “ Both sides are alike, the greater 
diameter is about one fouTth longer than the lesser ; the thickness 
about one fourth of the shorter diameter.” It appears evident that 
Sowerby had before him, when he wrote his description, more per- 
fect examples than those he figured. 
M. de Koninck observed upon the similarity between the JY. eom- 
^iressus of Sowerby and the N. mutahilis of M‘Coy, and suggested 
that the former was a variety of the latter b 
The Xautilus Mosque)ms of Tzvi-etsLOV ~ (=suhsulcatus, Trautschold 
(non Phill.)) somewhat resembles the present species, but the peri- 
phery is broader and not so concave, and the sutures are not so 
sinuous as in Sowerby’s species. 
Horizon. Carboniferous Limestone. 
Localities. Xaas and llathfarnham, near Dublin, Kildare, Bath- 
keale (Co. Limerick), and near Cork. 
Well represented in the Collection, which contains several very 
beautiful specimens, and includes Sowerby’s types figured in the 
‘ Mineral Conchology.’ 
Discites planotergatus, M‘Coy. 
1S43. Nautilus he.vaf/onus, de Koninck, Descrip, dos Anim. Loss, da 
Terr. Carbonifere de la Belgique, pi. xxv. f. 1 . {Not of J. Sowerby.) 
1843. Nautilus subsulcatux^ de Koninck, ibid. p. o48, pi. xxx. fi'. 6 «, 0 b 
(excl. ff. 6 c, 6 d). (Not of J. riiillips.) 
1844. Nautilus (Discites) planoterf/atiis, M‘Coy, Synop. Carboniferous 
Foss. Ireland, p. 18, pi. ii. f. 2 (three figures). 
1849. Nautilus planotergatus, d’Orbigny, Brodr. de Paleont. Stratigr. 
vol. i. p. 110. 
1852. Nautilus jdanoterrjatus, Giebel, Fauna der Vorwelt, Band iii. 
Abtb. i. p. 177. 
18G0. Discites planotenjatus, Griffith, Jouru. Geol. Soc. Dublin, vol. ix. 
p. 5(3. 
1878. Nautilus jdanoterr/atus, de Koninck, Fauue du Calcaire Car- 
bonifere de la Belgique (Ann ales du Mus. Boy. d’Hist. Nat. de 
Belgique, tom. ii.), p. 117, pi. xxvi. ff. 1, 2, 3 a, 3 6, 3 c*. 
‘ Faune du Calcaire Carbonifere de la Belgique (Annales du Mus. Eoy. 
d’Hist. Nat. de Belgique, tom. ii.), 1878, pt. i. p. 122. 
2 M4moire3 du Comite Geologique [Eussia], vol. v. no. 3, 1888, p. 52. 
