Catalogue of Dark Nebulae.

A catalogue of dark nebulae has been compiled from a study of the red and blue prints of the National Geographic-Palomar Observatory Sky Atlas. The catalogue contains positions, both equatorial and galactic, for the centers of the clouds, values of their sizes in square degrees, and estimates of their opacities. Total areas obscured by clouds are tabulated as a function of latitude, and average sizes and distribution of the dark nebulae are given.