Since the publication of the first Atlas of Mammalian Chromosomes in 1967 the continuous compilation of mammalian karyotypes has become a useful instrument in cytologic and taxonomic studies. Technical advances in preparing mitotic cells from nonmammalian vertebrates have since allowed a better comparison of taxa in fishes, amphibia, reptiles, and birds. In these fields the literature is also widely scat tered; and it has become difficult to survey such information, published as well as unpublished, by nonspecialists. These were among the reasons for the new endeavor of compiling a chromosome...