203This article contains a brief review of previous research; chiefly, however, new d&ta concerning the fall of the Tungus, central Siberia, meteorite on June 30, 1908: New testimony of eyewitnesses was collected by the author and others in 1928-32. A map of the region of the fall has been plotted. The meteorological QOIlditions on the morning of June 30, 1908, have been studied on the basis of data from meteor~ogical stations in central Siberia. The atmospheric phenomena accompanying the flight were studied with the aid ofbarograms from Siberian and European stations as well as seismograms recorded at Irkutsk. On the basis of sound phenomena and data supplied by barograms and seismograms, the moment of the explosion of the meteorite was determined

Craters presenting unmistakable evidence of an impact origin have been excluded from the category of meteorite craters because no meteoritic materials have been found in or near them. The origin of certain silica‐glass deposits (closely resembling the glasses produced by fusion of siliceous materials in the intense heat incident to meteoritic impact with the surface of the Earth) is regarded as a mystery, because meteorites have not been found associated with these deposits. Attention is called in this communication to the possibility of the existence of contraterrene meteorites (defined in the paper), which would be just as capable of producing meteorite craters and silica‐glass as are ordinary meteorites, but of which no trace would remain after collision with the Earth.

This paper is devoted to a critical study of the natural glasses recently found in Val Verde County, Texas. On the basis of the behavior of these so‐called valverdites under the blowpipe flame; of their low densities and indices of refraction; of the crystallites and megascopic crystals contained in them; and of their other peculiarities, the conclusion is reached that they are not tektites, but are weathered pebbles of obsidian.

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