ZONE OF LYTOCBRAS JURENSE. 147 



Wiirttemberg as a distinct horizon demonstrated, and its leading fossils, Lyt. Jurense, 

 Harp, insif/ne. Harp, radians, Bel. digitalis^ and many others special to this zone, found 

 at Balingen, Heiningen, Wasseralfingen, and other localities, were described. Upon the 

 hard grey marls with Lyt. Jurense follow in Swabia beds of dark clay with Lyt. toru- 

 losum, as at Laufen and Metzingen. In Baden,^ as at Langenbriicken and Mingolsheim, 

 light grey calcareous marls with Lyt. Jurense, Harp, radians^ Bel. irreyidaris, Bel. 

 tripartitus, and Bel. acuarius, rest upon the Posidonomya-clays and form the uppermost 

 beds of the Lias in this region. 



In North Germany the Jurense-zonQ has been described by von Strombeck, Ewald, 

 and Credner as found in the Helmstedt, Halberstadt, and Harzburg Jura, and in all 

 these yielding its leading fossils as Lyt. Jurense, Harp, insiyne, Lyt. hircinum, Harp. 

 variabile, Harp, striatulmn, and Bel. irregularis. 



M. Terquem^ has described a " Gres supra-liassique ou marly sandstone," near 

 Metz, Moselle, which appears to represent this zone, as he has collected therefrom, in the 

 environs of Thionville and at Longwy, several of the characteristic fossils of the Jurense- 

 bed, as Harp, insigne, Harp, radians, Bel. tripartitus, together with Gastropods and 

 Laraellibranchs belonging to this horizon. 



At Silzbrunnen, Lower Elsace, my friend Professor K. Lepsius^ has described the 

 Jurensis-Mergel. The fossils he found were in very good condition, and the Ammonites 

 had their shells well preserved. In the marl the group of Harpoceras radians was the 

 most abundant. Here he collected likewise Lyt. Jurense, Lyt. Jiircinum, Harp, 

 insigne. Harp. Aalense, Harp, subplanatum. Harp, discoides, with Nucula Hammeri, Lima 

 Galatea, Lima dupilicata, Pecten textorius, Pentacrinus Jurensis, and Diastopora 

 liasica. 



On the right bank of the Drome, in the quarries of Suble, near Bayeux, above the 

 calcareous and argillaceous strata, with Harp, bifrons ow^l. Stephan. commune, M. H. Harle^ 

 discovered marly beds, two metres thick, containing Harp, opalinum, Harp, radians, Harp. 

 Comense, Harp, variabile, Bel. tripartitus, Bel. abbreviatus, Bel. longisulcatus, and Rhyn. 

 ringens, which evidently represent the Opalinum- and Jurense-zones in Calvados. 



At Thouars, Deux Sevres, it will be seen (p. 137) that the strata Nos. 1 — G 

 represent the Jurense-zone, which here rests conformably on the Serpentin/nn-heds. At 

 Verpillicrc and St. Quentin (Isere) Dr. OppeP collected Harp, radians. Harp, costula. 

 Harp. TJiouarsense, Harp. Comense, Harp, insigne. Harp. Aalense, Harp, comptum. 

 Harp, variabile, Lyt. Jurense, and Jjyt. hircinum. 



1 Leonliard, ' Geognost. Skizze des Grossherzog Baden,' p. 98, 1861. 



2 ' Paleontol. du Depart, de la Moselle,' p. 23, 1855. 



^ 'Beitriige zur Kenntniss der Juraformation in Unter-Elsass,' p. 13, 1875. 



^ ' Apercu de la const, geologique du Dep. Calvados,' Annuaire, 1853. 



» ' Juraformation Englands, Frankreiclis, und des S.-W. Deutschlands,' p. 233, 1856. 



