radii and that the galaxies are fully dark-matter dominated; their detected baryonic component is less than 4% of the total mass. This last conclusion is valid at least as long as we do not accept any of the more exotic theories of gravitation. The LSB galaxies lack bulges, bars, and nuclear activity, as well as CO or IR emission (have no molecules or dust).

There have also been a few intriguing reports of presumably intergalactic dust clouds. A cloud with 0.5-1.2 mag of extinction was identified in Microscopium by Hoffmeister (1962). Three other similar objects were listed by Rudnicki (1986); they extinguish background objects by 0.57 to 1.2 mag. In all reports the main point of contention was the actual distance to the cloud, which could put it in extragalactic space but could also locate it in the halo of the Milky Way (MW). Sometimes, the argument for an extragalactic location was based on a comparison of the properties of objects whose distance could be estimated and which were located behind the cloud with those of similar objects clearly not within the cloud limits (RR Lyrae stars; Murawski 1983).

The extragalactic nature is only fairly confidently established for the Abadi-Edmunds 