LYTOCERAS FIMBRIATUM. 407 



In the Lias it appears in the Marlstone (Middle Lias) as Lyt. fimbriatum, and Lyt. 

 lineatum, in the Upper Lias in the zone of Ilarpoceras bifrons as Lyt. cornucopia, and in 

 the zone of Lyt. Jurense as Lyt. Jurense^ Lyt. hircinum, and Lyt. torulosum. 



Lytoceras fimbriatum, Sowerby. Pis. LXXI, fig. 1 ; LXXII, figs. 1 — 4. 



Ammonites fimbeiatus, Sowerhy. Min. Conchology, vol. ii, p. 145, pi. 164, 1817. 



— — Hann. Amm. et Goniat., p. 135, No. 79, 1825. 



— — Keferstein. Naturgesch., ii, 401, 1834. 



— — von Buck. Petrif. remarq., tab. viii, fig. 2, 1831. 



— — Roemer. Norddeutschen Oolithgeb., p. 194, 1836. 



— — Zieten. Versteinr. Wurternb., p. 16, tab. xii, fig. 1, 1830. 



— — d'Orbigny. Pal. Fr., Terr. Jurass., t. i, p. 313, pi. 98, 1842. 



— LINEATUS var. FIMBRIATUS, Qwews^erf^. FI6zgebirge"Wiirtemb.,p. 171, 1843. 



— — — Cephalopoden, p. 103, 1849. 



— LINEATUS, Oppel. Mittlere Lias Scbwabens, p. 50, 1853. 



— fimbkiatus, Morris. Catal. British Fossils, p. 292, 1854. 



— — Simpson. Yorkshire Lias, p. 40, 1855. 



— — von Sauer. Cephalopod, N. E., Alp., p. 62, pi. xxii, figs. 



1—4, 1856. 



— LINEATUS, Quenstedt. Der Jura, p. 134, tab. xvi, fig. 13, 1858. 



— riMBRiATUS, DMwzor^ter. Depots Jurassiques, partie iii, p. 92, 1869. 



— — Brauns. Untere Jura, p. 234, 1871. 



Lytoceras fimbriatum, Neumayr. Zeitschr. Deutsch. geol. Gesellsch., Bd. xxvii, p. 



893, 1875. 

 — — Tate and Blake. Yorkshire Lias, p. 297, 1876. 



Description. — This Ammonite was first figured and described by Mr. James Sowerby 

 from a specimen collected at Lyme Regis by the late Dr. Buckland. The fragment that 

 formed the subject of the Plate was very imperfect and has long been much misunderstood. 

 Sowerby ^ says '* that the mouth in a full-grown shell is furnished with an undulated 

 reflected lip or ruffle, and the more or less perfect formation of this at various periods 

 produces either undulating lines of growth, some of which are obtuse and others acute, 

 or thin, annular fimbriae surrounding the volutions at certain intervals. The obtuse lines 

 of growth are indented at their backs, but straight towards the mouth and indicate that the 

 undulation of the lip is strongest at the back of it. The whorls do not appear to have 

 been very numerous ; the shell is thin, and the margins of the septa have rounded lobes." 



The very beautiful specimens figured in Pis. LXXI and LXXII obtained from the 



Marlstone beds at Lyme Regis, exhibit in a satisfactory manner the anatomy of the 



shell of this splendid Ammonite. The shell is discoidal and formed of around, elongated 



cone, a little compressed on the sides and rolled up into a disk, the volutions of which 



1 ' Mineral Conchology,' vol. ii, p. 145, tab. clxiv. 



