116 
NATJTILOIDEA. 
Represented by numerous specimens, including the one figured by 
Phillips (loc. cit.\ which forms part of the “ Gilbertson Collection ” 
in this Museum. 
Orthoceras unguis, Phillips. 
? 1825. Conilites ungidatus, de Blainville, Manuel de Malacologie, 
p. 378, pi. xi. f. 4. 
1836. Orthocei'as iinguis, Phillips, Geol. of Yorkshire, pt. ii. p. 238, 
pi. xxi. f. 2, 
1843. Orthocei'as unguis, Portlock, Rep. on the Geology of Londonderry 
&c. p. 385. 
1844. Orthoceras (Campyloceras) unguis, M'Coy, Carboniferous Foss, of 
Ireland, p. 9. 
1844. Cyrtoceras unguis, de Koninck, Descrip, des Anim. Fossiles de 
Belgique, p. 524, pi. xlvii. ff. 8, a, b, c. 
1850. Cyrtoceras unguis, d’Orbigny, Prodr. de Paleont. Stratigr. prem. 
Tol. p. 112. 
1851. Cyrtoceras unguis, Giebel, Fauna der Vorwelt, Band iii. Abth. i. 
p. 204. 
1862. Campyloceras unguis, Griffith, Joum. Geol. Soc. Dubhn, vol. ix. 
p. 55. 
1876. Cyrtoceras unguis, Armstrong, Y’oung, and Robertson, Cat. of 
the Western Scottish Fossils, p. 58. 
1877. Cyrtoceras unguis, Barrande, Cephalopodes, Etudes g6n(5rales, 
pi. cccclxxxvii. case xii. 
1878. CyHoceras unguis, Barrande, Syst. Sil. de la Boheme, vol. ii. 
supplem. pi. cccdxxxvii. case xii. 
1880. CyHoceras unguis, de Koninck, Faime du Calc. Carbonifere de la 
Belgique, p. 18, pi. xxxiv. ff. 2-5. 
[Not 1854. Cyrtoceras unguis P, Roemer, Palaeontographica, Band iii. 
p. 93, tab. xiii. f. 28.J 
Char. Shell very slightly curved towards its pointed ex- 
tremity, and nearly straight in the superior portion. Transverse 
section nearly circular at first, but becoming oval at a slight distance 
from the initial point and preserving this form to the extremity of 
the anterior portion. The rate of tapering is about 1 in 5. The 
body-chamber is very large, making up about | of the total length 
of the shell. Septa rather approximate, not deep, undulating. 
Siphuncle very slender, almost filiform, and cylindrical ; central in 
the young, and subcentral in the adult. The surface is quite 
smooth. Some examples preserve traces of the original colouring of 
the test ; this consists of a great number of transverse bands of 
colour, alternately light and dark, the colour-bands being wider on 
the inferior third than upon the superior part of the shell, where 
they become indistinct, and finally disappear. Specimens are not 
