1862. The birds of Great Britain. London, published by the author, 5 vols., text unpaged, 367 plates, 1862. GRINNEL, J. 1901. The status of the Cedar Waxwing in California. Condor, 3(6):146-147, 1901. 1909. A new cowbird of the genus _Molothrus_. Univ. California Publ. Zool., 5:275-281, 6 figs. in text, 1909. GRISCOM, L. 1934. The ornithology of Guerrero, Mexico. Mus. Comp. Zool. Bull. 75:367-422, 1934. HAMILTON, W. J., JR. 1933. A late nesting waxwing in central New York. Auk, 50(2):114-115, 1933. HANNA, W. C. 1931. Nesting of the Bohemian Waxwing in British Columbia. Condor, 33(6):253-254, 1 fig., 1931. HEINROTH, O. 1924. Die Voegel Mitteleuropas. Berlin, Huge Bermuehler, 1:51-58, 1924. HELLMAYR, C. E. 1935. Catalogue of the birds of the Americas. Field Mus. Nat. Hist. Mus. Publ. 347, 8(pt. 8):vi + 541 pp., 1935. HOWELL, A. B. 1938. Muscles of the avian hip and thigh. Auk, 55(1):71-81, 2 figs. in text, 1938. 1944. Speed in animals, their specialization for running and leaping. Univ. Chicago Press, xi + 270 pp., 55 figs. 1944. HUDSON, G. E. 1937. Studies on the muscles of the pelvic appendage in birds. Amer. Midl. Nat., 18:1-108, 26 plates, 1937. 1948. Studies on the muscles of the pelvic appendages in birds II, the heterogeneous order Falconiformes. Amer. Midl. Nat., 39(1):102-127, 1948. KNOWLTON, F. H. 1909. Birds of the world. Henry Holt & Co., Ltd., xi + 873 pp., 15 plates, 233 figs. in text, 1909. KONODA, N. 1943. A dictionary of animals. Tokyo, 3 + 767 + 50 pp., profusely illustrated, 1943. KOSHANTSCHIKOV, I. 1930. Ein Beitrag zur Kenntnis der Okologie, Biologie, und Geographie des Zobels (_Martes zibellina_ L.). Zeits. fuer Okol. der Tierre, 19(2):291-320, 2 maps, 1930. LINSDALE, J. M. 1928. Variations in the Fox Sparrow (_Passerella iliaca_) with reference to natural history and osteology. Univ. California Publ. Zool., 30(12):251-392, 4 plates, 38 figs. in text, 1928. LITTLEFIELD, M. J., and LEMKAN, F. 1928. History of a Cedar Waxwing family. Bull. NE Bird-Band. Assoc., 4:85-89, 1928. LUCAS, F. A. 1897. The tongues of birds. U. S. Nat. Mus. Report for 1895, 1001-1019 pp., 2 plates, 1897. MCGREGOR, R. C. 1906. Notes on birds observed while traveling from Yokohama to Manila. Condor, 8(4):98-100, 1906. MATTHEW, W. D. 1939. Climate and evolution. N. Y. Acad. Sci., Spec. Publ., 1:xi + 223 pp., 1939. MAYR, E. 1942. Systematics and the origin of species. Columbia Univ. Press, xiv + 334 pp., 29 figs. in text, 1942. 1947. Ecological factors in speciation. Evolution, 1(4):263-288, 1947. MERRIAM, F. A.