The condensation product of 9, lO-phenanthrenequinone and ethyl acetoacetate and the isomer into which it is coiiverted by acids have been shown to be I11 and IV, respectively, rather than I and I1 as originally proposed by Japp, Klingemann and Streatfeild. Ultraviolet and infrared spectra provided the information essential for the new structural assignments. A number of compounds derived from I11 and IV that were prepared by earlier workers but ...