Resumo: In 1969 the author erected a new family of the Multituberculata, the Paulchoffatiidae, which contains four genera ranging from the Kimmeridgian of Portugal to the Purbeckian of Engaland. The type-genus, Paulchoffatia W. G. KUEHNE, 1961 and a second genus, Kuehneodon G. HAHN, 1969, were found in the Guimarota coal pit near Leiria, Portugal; the two others, Plioprion COPE, 1984 and Bolodon OWEN, 1871 come from the Purbeckian of Durdleston Bay, Swansea, Dorset, England.The rich Portuguese collection – containing not only associated elements of the dentition and many isolated teeth, but also important parts of the skull – has been described in detail by the author in 1969, where the differences between the Paulchoffatiidae and the Plagiaulacidae are also discussed. In this paper an attempt will be made to explore the evolutionary tendencies within the Paulchoffatiidae as known to day.

For this purpose only the dentition can be used successfully, because this part of the skeleton is the only one known in all four genera. The dentition of the Plagiaulacidae – Which does not descend from the Paulchoffatiidae but represents a parallel evolutionary branch – can be used for comparaison.

Resumo: Stratigraphy and microfossils of the layers of the coalmine Guimarota near Leiria (Portugal) are discussed. The age of the sediments can be assessed as Lower Kimmeridge.The described sediments have probably been formed in a lagoonlike basin mostly containing ± pure freshwater. The ostracods found in fresh- to brackish water sediments are described. Among them are two new genera: Leiria n. gen. and Poisia n. gen.. With the help of a discriminant analysis, Theriosynoecum hemigymnon n. sp., a very similar form to Theriostnoecum wyomingense (BRANSON) is separated from the latter.