ZONE OF LYTOCBRAS JURENSE. 147 



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

 Harp, insigne. Harp, radians, Bel. dit/ifalis, 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. torn- 

 losum, as at Laufen and Metzingen. In Baden,^ as at Langenbri'icken and Mingolsheim, 

 light grey calcareous marls with Lyt. Jurense, Harp, radians, Bel. irregularis, 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-zone 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, insigne, Lyt. Idrcinum, Harp. 

 variabile, Harpi. striatulum, and Bel. irregularis. 



M. Terquem^ has described a " Ores 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 

 Lamellibranchs belonging to this horizon. 



At Silzbrunnen, Lower Elsace, my friend Professor R. 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. Idrcinum, Harp, 

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

 Galatea, Lima duplicata, Pecten tecetorius, Pentacrinus Jurensis, and Biastojmra 

 liasica. 



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

 calcareous and argillaceous strata, with Harp, difrons and Steplian. commune, M.. H.H&rW 

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

 Comense, Harp, variabile, Bel. tripartitus, Bel. ahbreviatus, Bel. longisulcatus, and Bhyn. 

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



At Tliouavs, Deux Sevres, it will be seen (p. 137) that the strata Nos. 1 — 6 

 represent the Jurense-zone, which here rests conformably on the Serpentifimn-heds. At 

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

 Harp. Thouarsense, Harp. Comense, Harp, insigne. Harp. Aalense, Harp, coinptiim. 

 Harp, varialile, Lyt. Jurense, and Lyt. hircinmn. 



1 Leonhard, ' Geognost. Slcizze des Grossherzog Baden,' p. 98, 1861. 



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



2 ' Beitrage zur Kenntniss der Juraformation in Unter-Elsass,' p. 13, 1875. 



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



^ ' Juraformation Englands, Frankreichs, und des S.-W. DeutscLlands,' p. 233, 1856. 



