Dear readers, contributing authors, and friends of the Journal of the Czech Geological Society and Bulletin of Geosciences.

For decades, both journals published articles covering the same wide spectrum of geoscience topics. At present, an agreement between the Czech Geological Survey and the Czech Geological Society has been reached in co-ordinated effort to focus our journals on distinguished disciplines. Since January 2006, the Journal of the Czech Geological Society will publish papers on crystalline geology, petrology, mineralogy, geochemistry, tectonics, and related topics. At the same time, Bulletin of Geosciences will present papers dealing with palaeoenvironmental geology, and related topics. The editors will inform authors submitting papers for publication about the new profile of the journals during the interim period.

We believe the focused scope of our journals will help to elevate the scientific quality of contributions. This major change in the evolution of our journals is aimed at improving their standing at the competitive scene of international publishing media.

We value authors of future contributions and wish to encourage them in submitting their manuscripts. Together with critical readers, they play the most important role in improving the quality of our journals.

The Bulletin of Geosciences is a quarterly journal published by the Czech Geological Survey. The journal has a long tradition, having been published since 1925 (see www.geology.cz/bulletin, Bulletin of Geosciences, 2005, Vol. 80, No. 4, 239–243, for details). Since 2001, the Bulletin of Geosciences has had an international editorial board. All submitted papers are written in English and have been subjected to international peer review. The journal is also published electronically, and full-text articles are available, beginning with volume 77, on the Bulletin website (www.geology.cz/bulletin).

Volume 81 of the Bulletin of Geosciences is marked by a series of notable changes. By decision of the director of the Czech Geological Survey, Zdenìk Venera, following his agreement with the head of the Czech Geological Society, Petr Budil, the Bulletin of Geosciences is changing its scope. Beginning with volume 81, the Bulletin will publish new articles in the field of palaeoenvironmental geology, including palaeontology, stratigraphy, sedimentology, palaeogeography, palaeoecology, palaeoclimatology, geochemistry, mineralogy, geophysics, and related fields. The new editorial board has invited an international group of associate editors (see journal covers) to help ensure the scientific quality of the published papers. Together with the change in scope, a new design and new instructions for authors have been prepared (see journal covers or www.geology.cz/bulletin). Also beginning with volume 81, the scientific papers for the Bulletin of Geosciences can be submitted electronically (to bulletin@geology.cz) to simplify the manuscript submission and reviewing process.

I greatly appreciate the work of Lilian Švábenická and other members of the previous Editorial Board for their service for the Bulletin of Geosciences. One of the main characteristics of a good scientific journal is the stability of the scientific and technical quality of its articles, and our new team promises to continue this standard. This would not be possible without the help of all members of our new team of coeditors, associate editors, and executive and technical editors. In addition, the most critical factor influencing the quality of any journal is that it receives ample, scientifically significant manuscripts.
I look forward to working together with the new editorial board, with our reviewers, and with all of the contributing authors in building a good scientific journal.

Seven cystoid taxa, including one new species, are described or re-described from the Tøenice and Mílina formations (Lower Ordovician, upper Tremadocian) of the Prague Basin: Macrocystella cf. greylingi, Echinosphaerites concomitans, E. sp., Glyptosphaerites ferrigena, Paleosphaeronites crateriformis, P. grossularia and Pyrocystites sp. New data on the morphology of Paleosphaeronites, i.e., gonoduct canal and palatal plates in peristome, are presented. A fixo-sessile mode of life of Paleosphaeronites is documented by the specimens attached to trilobite exoskeletons. The described cystoid fauna is one of the earliest yet known, and indicates remarkable echinoderm diversity and favourable marine environment in the late Tremadocian in the European part of peri-Gondwana region. • Key words: Cystoidea, Rhombifera, Diploporita, taxonomy, Tremadocian, Prague Basin, Bohemia, Czech Republic.

MERGL,M. & PROKOP, J.R. 2006. Lower Ordovician cystoids (Rhombifera, Diploporita) from the Prague Basin (Czech Republic). Bulletin of Geosciences 81(1), 1–15 (10 figures). Czech Geological Survey, Prague. ISSN 1214-1119. Typescript received May 23, 2005; accepted in revised form January 12, 2006; issued March 31, 2006.

Michal Mergl, University of West Bohemia, Department of Biology, Klatovská 51, 306 19 Plzeò, Czech Republic; mmergl@kbi.zcu.cz • Rudolf J. Prokop, National Museum, Department of Palaeontology, Václavské nám. 68, 115 79 Praha 1, Czech Republic; rudolf.prokop@nm.cz

Abundant, morphologically moderately diverse, and well-preserved hexactinellid sponge spicules, mostly pentactines and hexactines, were collected from the lower Olešná Member of the Klabava Formation (Arenigian) of the Komárov area, Prague Basin. Demosponges, represented by lithistiid dendroclones and the large radiolarian genus Anacrusa, were identified in the acid-etched residue of (?) phosphatic clasts. The species Pyritonema feistmanteli is critically revised. • Key words: Porifera, Hexactinellida, Lithistida, Radiolaria, Arenigian, Ordovician, Prague Basin, Bohemia.

MERGL, M. & DURŠPEK, J. 2006. Sponge spicules and radiolarians from the Olešná Member of the Klabava Formation (Ordovician, Prague Basin, Czech Republic). Bulletin of Geosciences 81(1), 17–26 (7 figures, 1 table). Czech Geological Survey, Prague. ISSN 1214-1119. Typescript received May 25, 2005; accepted in revised form January 12, 2006; issued March 31, 2006.

Michal Mergl, University of West Bohemia, Department of Biology, Klatovská 51, 306 19, Plzeò, Czech Republic; mmergl@kbi.zcu.cz • Jan Duršpek, University of West Bohemia, Department of Biology, Klatovská 51, 306 19, Plzeò, Czech Republic; jan.dur@email.cz

At the GSSP for the Silurian-Devonian boundary at Klonk, Czech Republic, a comparatively poorly diversified palynomorph assemblage has been documented. The boundary interval is characterized by the predominance of thickand/or thin-walled prasinophytes (Leiosphaeridia spp., ?Pleurozonaria spp.), while the other organic-walled microfossil groups are relatively rare (chitinozoans, acritarchs, scolecodonts, certain prasinophytes, mazuelloids). The highest taxonomic diversity of palynomorphs has been documented in the uppermost Pøídolí and in the lower part of the Lochkovian. Such a pattern of distribution could be connected with transgressive and regressive pulses occurring at the boundary interval. • Key words: Silurian-Devonian boundary, acritarchs, prasinophytes, mazuelloids.

BROCKE, R., FATKA, O. & WILDE, V. 2006. Acritarchs and prasinophytes of the Silurian-Devonian GSSP (Klonk, Barrandian area, Czech Republic). Bulletin of Geosciences 81(1), 27–41. Czech Geological Survey, Prague. ISSN 1214-1119. Typescript received September 15, 2003; accepted in revised form January 12, 2006; issued March 31, 2006.

Rainer Brocke, Research Institute Senckenberg, Palaeobotany, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany; Rainer.Brocke@senckenberg.de • Oldøich Fatka, Charles University, Institute of Geology and Palaeontology, Albertov 6, 128 43 Prague 2, Czech Republic; fatka@natur.cuni.cz • Volker Wilde, Research Institute Senckenberg, Palaeobotany, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany; volker.wilde@senckenberg.de

Five sedimentation episodes ranging from Upper Cenomanian to Lower Turonian (Korycany Member of the Peruc-Korycany Formation and Bílá Hora Formation) are documented from new outcrops at the Chrtníky quarry, Bohemian Cretaceous Basin (BCB). The first episode belongs to the lower Metoicoceras geslinianum Zone and is recorded only as phosphatic intraclasts in younger beds. The second and third episodes (upper M. geslinianum Zone) are represented by coarse conglomerates separated by an interval of condensed sedimentation, phosphogenesis, and erosion of incompletely lithified deposits. The third sedimentation episode is cut by erosion. Probably after a stratigraphic gap, a fourth episode followed and included further shaping of the underlying erosion surface (formation of a hardground s. lat.), stromatolite growth and phosphogenesis (second interval of condensed sedimentation), corrosion and redeposition of diabase clasts, calcareous mud deposition and firmground formation, and, finally, deposition of dark claystone and burrowing. This succession seems to be of Early Turonian age, Whiteinella archaeocretacea (?) Zone. Basal portions of the fifth sedimentation episode (Lower Turonian, Helvetoglobotruncana helvetica Zone) started after the erosion event and included marly deposits rich in macrofauna, whereas the overlying strata yield an impoverished fauna predominated by sponges. In the topmost part of the succession, fully oxic conditions with abundant macrofauna are documented. The biostratigraphic conclusions are based on macrofauna and micropalaeontology (palynomorphs and foraminifera), and on correlations with other shallow-water successions (Pøedboj, Velim, Pecínov). Finds of enormously abundant remains of the crinoid Cyathidium aff. depressum (Sieverts) are unique. Common bryozoan and microfossil associations document a deepening of the basin during the fifth sedimentation episode. An identical development is documented by gradual changes in ecologic types of sponges (Pachytilodia bohemica→Chonella-Verruculina-Siphonia→Laocoetis-Guettardiscyphia-Diplodictyon assemblages). The taphonomy of macrofauna supports previous views of the geological and sedimentological developments in the area. Nontronite, which causes the greenish colour of clay laminae mainly in stromatolites, was identified for the first time in the BCB. • Key words: Bohemian Cretaceous Basin, Upper Cenomanian–Lower Turonian, taphonomy, palaeoecology, sedimentary environment.

ŽÍTT, J., VODRÁŽKA, R., HRADECKÁ, L., SVOBODOVÁ, M. & ZÁGORŠEK, K. 2006. Late Cretaceous environments and communities as recorded at Chrtníky (Bohemian Cretaceous Basin, Czech Republic). Bulletin of Geosciences 81(1), 43–79 (22 figures, 3 tables). Czech Geological Survey, Prague. ISSN 1214-1119. Typescript received October 3, 2005; accepted in revised form January 12, 2006; issued March 31, 2006.

Jiøí Žítt, Academy of Sciences of the Czech Republic, Institute of Geology, Rozvojová 135, 165 02 Praha 6; zitt@gli.cas.cz • Radek Vodrážka, Czech Geological Survey, Klárov 3/131, 118 21 Praha 2; Charles University, Faculty of Science, Institute of Geology and Paleontology, Albertov 6, 128 43 Praha 2; vodrazka@cgu.cz • Lenka Hradecká, Czech Geological Survey, Klárov 3/131, 118 21 Praha 2; hradecka@cgu.cz • Marcela Svobodová, Academy of Sciences of the Czech Republic, Institute of Geology, Rozvojová 135, 165 02 Praha 6; svobodova@gli.cas.cz • Kamil Zágoršek, National Museum, Václavské námìstí 68, 115 79 Praha 1; kamil.zagorsek@nm.cz

In the area of the Boskovice Basin, simple ichnoassemblages and ichnofabric patterns characterize a suite of lacustrine and fluvial deposits. The succession of ichnofabrics enables us to correlate several sections in the northern part of the basin, supporting the correlation of the previously recognized Baèov, Míchov and Obora horizons. The mostly finegrained lacustrine deposits below bituminous limestones contain Planolites beverleyensis, Planolites montanus, amphibian footprints, and rare Cruziana problematica. Reddish sandstones, which can be interpreted as alluvial plain deposits, contain Planolites, Scoyenia, “star-like traces”, and Diplocraterion. In the southern part of the basin, the coal-bearing strata are characterized by generally poor bioturbation, with isolated levels of “root spots” and Planolites. The lowermost strata of the overlying red-bed unit show intensive and rhythmical Planolites ichnofabric, the intensity and uniformity of which decrease upwards. • Key words: trace fossils, ichnofabric, Carboniferous, Permian, lacustrine and fluvial environment, Boskovice Basin.

MIKULÁŠ, R. & MARTÍNEK, K. 2006. Ichnology of the non-marine deposits of the Boskovice Basin (Carboniferous–Permian, Czech Republic). Bulletin of Geosciences 81(1), 81–91. Czech Geological Survey, Prague. ISSN 1214-1119. Typescript received March 16, 2005; accepted in revised form January 12, 2006; issued March 31, 2006.

Radek Mikuláš, Academy of Sciences of the Czech Republic, Institute of Geology, Rozvojová 135, 165 00 Praha 6, Czech Republic; mikulas@gli.cas.cz • Karel Martínek, Charles University, Faculty of Science, Institute of Geology and Palaeontology, Albertov 6, 128 43 Praha 2, Czech Republic; karel@natur.cuni.cz