Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/625

 TRANSLATIONS AND NOTICES

OF

GEOLOGICAL MEMOIRS.

Jurassic series from the Rhaetic formation up to the Neocomian has been found well represented in a circumscribed area near St. Veit, about $2 1⁄2$ miles north-west of Vienna. The Koessen strata are well developed and very fossiliferous; but their stratigraphical relations with the remainder of the Lias could not be ascertained. The Dogger is represented by the zones of Ammonites Sauzeanus, A. Humphriesianus, and A. Parkinsoni. These deposits strike N.E. and S.W., dipping N.W., and form, as it were, an island in the unconformable Upper Jurassic deposits.

The Klaus beds may possibly be represented by a fine red lime-stone containing Crinoids, and occurring in two localities, as it yields a Terebratula very similar to T. Roveredana, Benecke. This and another red limestone, the latter containing Aptychi, strike from E. to W., and dip S., overlying the Dogger unconformably, but they are conformably succeeded by the white Neocomian limestone, which yields Aptychus Didayi, Coq. The former has afforded Aptychus loevis, A. latus, A. gibbosus, A. lamellosus, A. crassicauda, Belemnites hastatus, and B. canaliculatus.

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In this preliminary pamphlet the author announces a remarkable discovery that he has made, namely, that various "eruptive" rocks, such as the melaphyre of Zwickau and the Thuringerwald and the porphyry of Halle, contain the microscopic remains of organisms imbedded in thin crystalline constituents, and not merely in the calcite and other materials by which spaces in the rock have been filled up. His observations were made upon cut and polished sections of the rocks, taken not from the surface (where weathering might interfere), but usually from quarries.

The organic forms detected by Dr. Jenzsch in these rocks are characteristic of standing fresh water. No Diatomaceae have occurred to him; and of the Carapaced Infusoria, only a few Arcellæ have been met with. Of plants, he says that he has met with entire well- VOL. XXV.—part II. B