346 THE LIAS AMMONITES. 



Abgocekas Davcei, Sowerhy. PL XXXI, figs. 1, 2. 



Ammonites Davoei, Sowerhy. Min. Conch., vol. iv, p. 71, pi. 350, 1822. 

 Planites — de Haan. Ammonit. et Goniatit., p. 82, No. 3, 1825. 

 Ammokites — Zieten. Versteiner. Wurttembergs, p. 19, tab. xiv, fig. 2, 1830. 



— — Boemer. Norddeutschen Oolithgebirg., p. 199, 1836. 



— BAVom, Jironn. Letheea geognost., p. 447, tab. xxiii, fig. 4, 1837. 



— — Collegno. Bulletin Soc. g^olog. de France, x, p. 247, 1839. 



— — Quenstedt. Flozgebirge Wiirtembergs, 171, 1843. 



— Dav^i, d'Orhigny. Pal. Fran9. Juras., torn, i, p. 276, pi. 81, 1842. 



— — Quenstedt. Cephalopoden, p. 91, tab. 5, figs. 6, 1849. 



— — Savi and Meneghini. Consid. Geologia Toscana, p. 115, 1851. 



— — Studer. Geologie der Schweiz, t. ii, p. 31 — 35,1853. 



— — Meneghini. Nuovi Fossili Toscani, pp. 10, 31, 1853. 



— Datoi, Oppel. Mittlere Lias Scliwabens, Jahreshefte Wiirttemberg, p. 80, 



1853. 



— — Quenstedt. Der Jura, p. 132, 1858. 



— — Von S.auer. Die Cephalopoden aus dem Lias der Nord-Ost. 



Alpen, p. 54, pi. xvii, figs. 11, 12, 1S56. 



— — Ghapuis. Terr. Sec. de Luxemb., p. 25, t. iv, fig. 5, t. v, fig. 1, 



1858. 



— — Bumortier. Dep6ts Jurassiques du Bassin du Rhone, torn, iii, 



p. 94, pi. xi, figs. 4—6, 1869. 

 Aegocekas Davoei, Neumayr. Zeitschrift der Deutsch. geol. Gesellschaft, p. 906, 

 1875. 



Diagnosis. — Shell discoidal, depressed ; umbilicus wide ; whorls round, slightly 

 involute, covered on the sides and area with numerous simple, narrow, oblique ribs ; on 

 each revolution of the spire there are eight to ten round, obtuse 

 tubercles developed near the middle of the whorl, and occu- 

 pying the width of three ribs ; siphonal area rounded, slightly 

 depressed, and covered with numerous transverse close-set 

 costse; spire formed of eight whorls, which are round and 

 slightly depressed on the outer margin ; aperture roundish. 



Dimensions. — The large figured specimen ; transverse dia- 

 meter 112 millimetres; width of umbilicus under aperture 65 

 millimetres ; vertical height of whorl 26 millimetres ; transverse 

 diameter 30 millimetres. The specimens found in general are 

 Sow. much smaller, two beiore me measure transverse diameter 90 



milhmetres; width of umbilicus under aperture 55 millimetres; vertical height of last 

 whorl 22 millimetres ; transverse diameters 23 millimetres. 



Description. — This beautiful Ammonite is a very rare British fossil. The specimen 



