Released by ATF in 1938–40, with Bold Condensed styles following in 1946 [Reichardt 2011]. In addition to the italic styles, there is also a calligraphic Lydian Cursive.
The Smithsonian has drawings for an unreleased Extra Bold which seemed to predate the other styles [Frere-Jones via email]. The University of Amsterdam also holds drawings, proofs, and correspondence (dated 1953–55) for Light and Bold “Capella” intended to be Typefoundry Amsterdam’s adaptation of Lydian [UvA].
Digitizations by Bitstream (Roman, Italic, Bold, Bold Italic, Cursive) and Monotype (Roman and Cursive). The condensed styles have been revived as Lydia (Colophon, 2013).