A Vireo Specimen with Supernumerary Rectrices
A Vireo Specimen with Supernumerary Rectrices.-There are few records in the literature of passerine birds with supernumerary rectrices, although Arthur A. Allen informs me that they are not uncommon in the Ruffed Grouse (Bonaca umbellus) and perhaps in other gallinaceous birds. It may be of interest, therefore; to record such an occurrence recently discovered in a specimen in the Louis Agassiz Fuertes Memorial Collection at Cornell University. The bird (C. U. 15791) is a male Carmiol Vireo (Vireo carmioli) of undetermined age, collected by Austin Paul Smith at 9000 feet elevation on Volcan Turrialba, Costa Rica, on November 24, 1922. The specimen seems perfectly normal in all respects, save that it possesses no less than fifteen rectrices. All are fully grown, with no trace of sheathing at the bases of the feathers. The three extra feathers are, morphologically, of the type of the normal central pair, with the rachis centrally located. As far as can be determined . without damaging the specimen, the follicles have been duplicated laterally rather than dorsoventrally, thus making it difficult to ascertain precisely which three of the five “central” rectrices are the supernumeraries. The exact stage of development at which this duplication arose is, of course, purely conjectural.-KENNETH C. PARKES, Laboratory of Ornithology, Cornell University, Ithaca, New York, October 17, 1949.