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the literature is also widely scat­ tered; and it has become difficult to survey such information, published as well as unpublished, by nonspecialists.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 atlas for nonmammalian vertebrates. An annual publication is planned with presentation of between 10 and 15 karyotypes from each class. In this second volume, 52 species are presented. For convenience in future colation, the numbering system employs class abbreviations, viz. , P-Pisces, Am-Amphibia, R-Reptilia, and Av-Aves. Within each class, the numbers are necessarily consecutive. In general the karyotypes are laid out following the format employed in An Atlas of Mammalian Chromosomes. Whenever possible both sexes are represented, even though sexual chromosomal dimorphism is not (currently) evident. When the sex chromosomes are known, they are so indicated by conventional nomenclature (XX/XY or ZW /ZZ). In the karyotypes of birds the so-called microchromosomes are grouped together at the end without an attempt at complete enumeration, which is presently impossible. They are usually considered as acrocentrics, but a few are distinctly biarmed.

Perciformes.- Morone americana (Gmelin) (White perch) 2n = 48.- Perca flavescens (Mitchill) (Yellow perch) 2n = 48.- Atheriniformes.- Megupsilon aporus (Miller and Walters) 2n = 47(?), 48 (?).- Siluriformes.- Noturus gyrinus (Mitchill) (Tadpole madton) 2n = 42.- Ictalurus nebulosus (Lesueur) (Brown bullhead) 2n = 60.- Cypriniformes.- Catostomus commersoni (Lacépède) (White sucker) 2n = 100.- Anura.- Bufo regularis 2n = 20.- Bufo valliceps (Wiegmann) (Gulf Coast toad) 2n = 22.- Hyla chrysoscelis (Cope) (Southern gray treefrog) 2n = 24.- Hyla cinerea (Schneider) (Green treefrog) 2n = 24.- Hyla versicolor (LeConte) (Eastern gray treefrog) 2n = 48.- Scaphiopus bombifrons (Cope) (Plains spadefoot toad) 2n = 26.- Scaphiopus couchi (Baird) (Couch's spadefoot toad) 2n = 26.- Rana catesbeiana (Shaw) (Bullfrog) 2n = 26.- Rana nigromaculata (Hallowell) (Black-spotted, or Tonosama frog) 2n = 26.- Rana pipiens sphenocephala (Cope) (Southern leopard frog) 2n = 26.- Rana sylvatica sylvatica (LeConte) (Eastern wood frog) 2n = 26.- Urodela.- Pleurodeles waltli (Michahelles) (Spanish ribbed newt) 2n = 24.- Squamata.- Bothrops alternatus (Duméril, Bibron et Duméril) (Urutu cruzeiro; Jararaca rabo de porco) 2n = 36.- Clelia occipitolutea (Duméril, Bibron et Duméril) (Black snake Muçurana; Cobra preta) 2n = 50.- Drymarchon corais corais (Boie) (South American indigo snake; Papa-ovo; Papa-pinto) 2n = 36.- Liophis miliaris (Linnaeus) (Cobra d'agua) 2n = 28.- Mastigodryas bifossatus bifossatus (Raddi) (Panther snake; Jararacuçu do brejo; Nyakaniná) 2n = 36.- Philodryas serra (Schlegel) (Cobra cipó) 2n = 28.- Spilotes pullatus anomalepis (Bocourt) (Chicken snake; Caninana; Caninana do papo amarelo; Yacaniña) 2n = 36.- Xenodon neuwiedii (Günther) (Neuwied's snake;Quiriripitá) 2n = 30.- Amphisbaena dubia (Müller) (Worm lizard; Cobra de duas cabeças) 2n = 26(25, 27, 28).- Amphisbaena vermicularis (Wagler) (Worm lizard; Cobra de duas cabeças) 2n = 44.- Leposternon microcephalum (Wagler) (Cobra de duas cabeças) 2n = 34.- Mabuya mabouya mabouya (Lacépède) (Mabuya; Lagartixa) 2n = 30.- Ophiodes striatus (Spix) (Glass snake; Cobra de vidro) 2n = 36.- Tropidurus torquatus (Wied) (Calango) 2n = 36 (37, 38).- Rheiformse.- Rhea americana (Rhea) 2n = 82.- Charadriformes.- Charadrius vociferous (Killdeer) 2n = 76.- Passeriformes.- Corvus corax (Raven) 2n = 78.- Strigiformes.- Bubo virginianus (Great horned owl) 2n = 82.- Apodiformes.- Calypte anna (Anna's humming bird) 2n = 74.- Galloformes.- Lophortyx gam belli (Gambell's quail) 2n = 80.- Anseriformes.- Aix galericulata (Mandarin duck) 2n = 90.- Aix sponsa (Wood duck) 2n = 80.- Cairina moschata (Muscovy duck) 2n = 78.- Dendrocygna bicolor (Fulvous tree duck) 2n = 80.- Anas acuta (Pintail duck) 2n = 82.- Anas clypeata (Common shoveler) 2n = 78.- Anas discors discors (Prairie blue-winged teal) 2n = 80.- Anas platyrhynchos platyrhynchos (Mallard and its domesticated varieties) 2n = 80.- Anas streptera (Gadwall) 2n = 80.- Aythya valisineria (Canvasback) 2n = 80.- Aythya affinis (Lesser scaup) 2n = 80.- Aythya Americana (Redhead) 2n = 80.- Tadorna tadorna (Common shelduck) 2n = 80.- Bucephala clangula americana (American goldeneye) 2n = 80.- Erratum.- Erratum.