CTRTOCEEATIDJ!. 
309 
1876. Cyrtoceras rugosum, Armstrong, Young, and Eobertson, Cat. of 
the Western Scottish Fossils, p. 58. 
1877. Cyrtoceras {Orthoceras) rugosum, Barrande, Syst. Sil. de la 
Boheme, yoI. ii. Supplem. pi. cccclxxxvii, case x. (after Phillips). 
Sp. Char. “ Subcylindrical, and nearly straight when old, 
abruptly and irregularly tapering, and moderately curved towards 
the smaller end ; section circular ; surface girt with equal, obtusely 
rounded, very prominent, irregularlj^-waved, slightly oblique rings 
(having two septa in the space between each pair of rings); 
interannular spaces flat, and slightly more than twice the thickness 
of the rings in width ; rings nodulated by the crossing of about 
twenty-six equal, filiform, slender, tuberculated ridges, separated by 
flat spaces nearly twice their width, such spaces being at least 
twice as long as wide (four ridges and three intervening spaces 
equalling the space from the centre of one transverse ring to the 
other) ; septa moderately convex ; siphon very minute, close to the 
margin (coinciding with the convex aspect of curved specimens, and 
at the higher edge of the septa and external rings). Specimens 
five lines in diameter have their rings two lines from centre 
to centre ; specimens one inch in diameter have their rings on the 
sides, about three lines from centre to centre, but five lines on the 
exterior and only two lines on the inner aspect of curved specimens. 
“ This species tapers so irregularly, and the fragments are so short, 
that any measurements of their proportions would be deceptive. 
Some of the large specimens show traces of very fine, close, transverse 
striae.” {M’-Coy.) 
Remarhs. M. de Koninck expresses the opinion that the present 
species is identical with the 0. reticulatum of Phillips {ante, 
p. 108), but the latter is a perfectly straight shell, and tapers less 
rapidly than C. rugosum. 
Horizon. Upper Limestone Grouph 
Localities. Lanark ; Orchard Quarry, near Glasgow. 
Eepresented in the Collection by three specimens, one of which 
(No. 80385 in the Eegister) has no locality recorded against it. 
Cyrtoceras (Meloceras) ornatum, Eichwald, sp. 
1840. Amplexus ornatus, Eichwald, Bull. Scient. de I’Acad. des 
Sciences de St. Petersbourg, p. 17. 
1844. Cyrtoceras rugosum, de Koninck, Descrip, des Anim. Fossiles de 
la Belgique, p. 527, pi. xliv. f. 8, pi. xlvii. f. 7. 
? 1849. Cyrtoceras rugosum, d’Orbigny, Prodr. de Paleont. Stratigr. 
vol. i. p. 112. 
Carboniferous Limeitone Series (see footnote, p. 121). 
