52 EOCENE MOLLUSCA. 



siphuncle, by which only the position can be determined, is perfectly marginal. The 

 Nautilus Aturi, which I consider to be identical with Nautilus zic-zac, is the type of 

 Bronn's genus, and I therefore retain the name proposed by that author, although I do 

 not assent to the accuracy of his generic description. 



The genus Clymenia, proposed by Count Munster for certain Nautiliform remains 

 occurring in the transition limestones of Fichtelgebirge, presents nearly the same 

 characters as those assigned by me to Aturia ; except that in Clymenia the whorls are 

 exposed, and the siphuncle is described as narrow ; whereas in Aturia the last whorl 

 conceals the others, and the siphuncle, at least in A. zic-zac, the typical species, is of 

 great size. 



The genus appears to have been confined to the tertiary epoch, and it is widely 

 diffused. It occurs in the Eocene formations of England, France, Belgium, and 

 Germany ; in the Miocene deposits in the basins of the Gironde, in Italy, and in Malta. 

 It is also found in the Eocene formation in Clarke county, Alabama, (U. S.), and Conrad* 

 mentions a cast from the contemporaneous formation near Long Branch, New Jersey, 

 resembling Nautilus (Aturia) zic-zac, but more compressed, and which he has referred 

 to De Montfort's genus Pelayus, and has named P. Vanuxemi. De Montfort's Pelayus, 

 however, is described as having " cloisons lobees, persillees, dentelees, &c." The 

 position of the siphuncle is not mentioned in De Montfort's text ; but in the figure he 

 has given it is placed on the ventral margin. The shell, therefore, on which the 

 genus Pelagus is founded is an Ammonite, and the species constituting the present 

 group cannot be associated with it. 



No. 13. Aturia zic-zac. Bronn. Tab. IX, fig. \a — h. 



Var. a. Nautilus zic-zac. Sow. 1812. Min. Con. vol. i, p. 9, pi. 1, fig. 3. 

 Ammonites Wapperi. Van Mons. 1833. L'Institut. 1833, p. 272. 



— — — 1834. Bull, de l'Acad. de Brux. tome i, No. 17, 



pp. 113, 118. 

 Nautilus Deshayesii. Be Koninck. 1834. Notice sur un Moule pyriteux du Naut. de 



Desh. ; Bull. Soc. Geol. de France, t. iv, p. 43/. 



— — Nyst. 1835. Rech. sur les Coq. foss. de la Prov. d' An vers, 



p. 35, No. 52. 



— — De Koninck. 1837. Desc. des Coq. foss. de l'Argile de 



Basele, p. 1. 



— Atuei. Bronn. 1837. Leth. Geog. vol. ii, p. 1123, pi. 42, fig. 17a— c. 



— zic-zac. Desh. 1837. Desc. des Coq. foss. des Env. de Paris, vol. ii, p. 765, 



pi. 100, figs. 2, 3. 

 Clymenia zic-zac. Michelotti. 1840. Annal. Scient. reg. Lomb. Venet. p. 6. 



* Conrad's " Observations on the Eocene formation, and description of one hundred and five new fossils 

 of that period, from the vicinity of Vicksburg, Mississippi," published in the Journal of the Academy of 

 Natural Science of Philadelphia. 



