160 
NAUTILOIDEA. 
Temnocheilus bidorsatus, Schlotheim, sp. 
1710. Nautilitis &c., Buttner, Rudera diluvii testes, p. 271, Paragr. 
162, Tab. XXX. 
1775. Navtilites, &c., Knorr & Walch, Reciieil des Monumens des 
Catastrophes de la Terre, &c. tom. iii. p. 150, Suppl. pi. v. h. 
1818. Nautilus arietis, Reiiiecke, Maris protogaei Nautilos et Argo- 
nautas, p. 88, pi. x. f. 70. 
1820. Nautilus hidorsatus, Schlotheiiii, Die Petrefactenkunde, p. 82, 
pi. xxxi. ff. 2a, 2h, 2c. 
1829. Nautilus bidorsaius, Broun, in Leonhard, Zeitschr. Band i. j). 74. 
1830. Nautilites bidorsatus, Zieteii, Les Petrifications de Wurteniberg, 
p. 23, tab. xviii. fF. la, 16, Ic. 
1831. Nautilus bidorsatus, Mlinster, Bull. Soc. Geol. de France, toin. i. 
p. 182. 
1832. Nautilus bidorsatus, Goldfnss, in von Dechen’s translation of De la 
Beebe’s Handbook of Geology (Ilandbiich der Geognosie), p. 456. 
1837. Nautilus bidorsatus, Bronn, Lethaea Geognostica, Band i. p. 177, 
tab. xi. ff. 21, a, b. 
1849. Nautilus bidorsatus dolomiticus, Quenstedt, Petrefactenkunde 
Deutschlands, Band i. Abth. i. p. 54, Taf. ii. If. 13a, 136. 
1849. Nautilus arietis, d’Orbigny, Prodr. de Paleont. Stratigr. vol. i. 
p. 171. 
1852. Nautilus arietis, Giebel, Fauna der Vorwelt, Band iii. ^Vbth. i. 
p. 156. 
1861. Nautilus bidorsatus, G umbel, Geogn. Beschreib. des barer ischen 
Alpengebirges und seines Vorlandes (Geogn. Beschreib. des 
Koenig Bayern), Abth. i. p. 858. 
1865. Nautilus bidorsatus, Eck, Ueberdie Forniationen des Bunten 
Sandst. u. d. Muschelkalks in Oberschlesien und ihre Verstein. 
p. 141. 
1868. Nautilus bidorsatus, Terquem et Barre, Descrip. Geologique et 
Mineralogique du Departement de la Moselle par Jacquot, p. 159. 
1870. Nautilus bidorsatus, F. Roemer, Geologie von Oberschlesien, 
pp. 135, 146. 
1880. Nautilus bidorsatus, Eck, Beitrag zur Kenntniss des siiddeutschen 
Muschelkalks, in Zeitschr. der Deutsch. geol. Gesell. Band xxxii. 
p. 50. 
1880. Nautilus bidorsatus, Mallada, Boletin de la Comision del Mapa 
Geologico de Espana, vol. vii. Sinopsis de las Especies Fdsiles de 
Espafia, p. 3, pi. i. If. d, 2. 
S]o. Char. Shell thick, discoid, composed apparently of about 
slightly embracing whorls, which are all exposed in a very deep 
umbilicus. The section is irregularly six-sided, and always more 
or less wider than high. The periphery is broad and furrowed, and 
its angles rounded. The sides are compressed and slope a little 
outwards towards the margin of the umbilicus. The latter has an 
