Rectification of two generic names

I am sorry to say that amongst the new generic names, occurring in my recent paper on the genus Pycnonotus and some allied Genera (N. L. M. XVII), Centrolophus and Gymnocrotaphus are already preoccupied among the Fishes, the first being used by Lacépède, the second by Günther. I propose, therefore, to substitute the name Centrolophus (pp. 226 and 230) by Bostrycholophus (curlcrest) on account of the upward-bent longer crest-feathers, and the name Gymnocrotaphus (pp. 227 and 245) by Bonapartia, Bonaparte being the author of the single species of this peculiar genus.