Foraminifera from the Silberberg Formation («Lower Oligocene») at Silberberg,near Helmstedt (Germany)

From the Silberberg Quarry, type locality of the Silberberg Formation (Martini &Ritzkowski 1968), some planktonic foraminifera are described:Globigerina officinalis Subbotina, Globigerina ouachitaensisHowe &Wallace,G. praebulloides leroyi Blow &Banner, G.praebulloides occlusa Blow &Banner which taxa are here suggested to form intergrading morphotypes within the range of variation of a population dominated byG. officinalis. In addition,G. cf.danvillensis Howe &Wallace is found. The planktonic fauna, together with some elements in the benthonic fauna, suggests a possible correlation with the Danville Landing Member of the Jackson Formation, Louisiana, traditionally ascribed to the Upper Eocene. There is some similarity with European Uppermost Eocene — Lower Oligocene faunas described by various authors. The Silberberg Formation was suggested to be a Neostratotype for the Latdorfian Stage of the Lower Oligocene byMartini &Ritzkowski (1968). It is suggested that the Silberberg Formation may well be coeval with the Upper Priabonian as proposed byCita 1969.     

Heterochromatin distribution and chiasma localization in the grasshopper Bryodema tuberculata (fabr.) (Acrididae)

The problem of extreme localisation of chiasmata in the grasshopper species Bryodema tuberculata has been reinvestigated, using C-banding, Q-banding and benzimidazol techniques. These techniques reveal the precise localisation of heterochromatin in different chromosomes. Single or double heterochromatic blocks are present near the centromeric regions, except in chromosomes 5 and 11, which have larger blocks. These two chromosomes possess a distal chiasma while the other autosomes have a proximal chiasma. The results with regard to the distribution of chiasmata, in relation to the localisation of heterochromatin, as well as the existence of a short arm, are compared with the earlier observations of White, and discussed briefly.