Favosites, a family of fossil corals belonging to the hydroid acalephs. Their cells are divided by horizontal partitions, like those of the millepores, which, according to Agassiz, are true acalephs: but the species are so polyplike that until recently they were classed with the polyps. According to 1 )ana. they are a comprehensive type, intermediate between the polyps and the higher acalephs, and having some of the characters of both. They are all paleozoic, especially Devonian and upper Silurian.