sampling for a species close to the median of the distribution (Great Blackhawk Buteogallus urubitinga) was scattered and inappropriate for statistical analysis, Results suggest strongly that sampling of Mexican birds is incomplete, that continued scientific collecting is needed to complete…

Environmental assessments of regional development projects have been used in Mexico to determine where conflicts between conservation of biodiversity and resource extraction are likely to occur. Speciesrich areas have been acknowledged as a priority for conservation. However, biological information is…

The purpose of the present paper is to review the current knowledge about cholesterol gallstone disease. It is generally accepted that the formation of cholesterol gallstone requires three major pathogenic defects, namely, supersaturation, nucleation and crystal growth as well as…

These notes contain a series of ten lectures delivered at the ''Universidad Nacional Autonoma de Mexico'' on its ''Primer Seminario de K-Teoria Algebraica''. They provide an introduction to the subject as well as to the other expositions in this volume.…

The compressed basidiocarp of a fungus belonging to Geasteraceae (Lycoperdales, Gasteromycetes) was recovered from the plant-bearing Cenozoic strata of the Pie de Vaca Formation, Puebla, Mexico. The fossil specimen consists of an open exoperidium with ten triangular rays, and a…

Mimosoideae), Mimosa (Mimoseae, Mimosoideae), Lysiloma (Ingeae, Mimosoideae),and Sophora (Sophoreae, Papilionoideae). Another fruit exhibits a combination of characters unknown among extant legumes, and although superficially similar to some species of Papilionoideae, it represents an extinct genus. The four identified genera are…

The Upper Cenozoic flora of the Pie de Vaca Formation, Puebla, Mexico, is yielding important elements that contribute to a more complete knowledge of the Tertiary floras of southern latitudes of North America. Among the most abundant plant organs in…