ZOOLOGY.] AMERICA 083 Megatherium americanum. Mylodon giganteus. gracilis. robustus. darwinii. Scelidotherium leptoceplialum. cuvieri. Megalonyx mcridionalis. jeffersoni. Equus curvidens. devillei. Toxodon burmeisteri. owenii. Mastodon humboldtii. Some of these also occur in Brazil, where species have also been found belonging to the genera Callithrix, Cebus, Protopithecus, Chlamydotherium, Coelogenys, Colodon, Dasypus, Equus neogaeus, Equus principalis, Euryidon, Heterodon, Hoplophorus, Myrmecophaga, Nesodon, Pachy- therium, and Xenurus. Remains of many of these genera have also been found on the banks of the Rio Negro in Uruguay, and those of some, such as Mastodon, Equus, Auchenia, &c., in Ecuador. As space forbids our dwelling upon the points of interest which these fossil forms present, we pass on to the lists of the extinct faunas of North America. The oldest species yet found in North America belongs to Dromatherium, and was found in the Triassic beds of Virginia. Then nothing is known until we come to the Tertiary deposits which were formed in lakes along the base and in the midst of the Rocky Moiintains and neighbouring ranges, and in the marine beds which lie nearer the pre sent sea margin. The following lists are given by Dr Leidy, 1 who considers the oldest beds in Nebraska, which rest on the Cretaceous series, as of Miocene age. They contain Titanatherium prouti, Lophiodons, and several other forms which would induce us to regard them as Eocene. However, we follow his lists. The Miocene species are Carnivora. Canidse. Aniphicyon vetus. gracilis. Hyaenodontidse. Hytenodon horridus. cruentus. crucians. Folidae. Drepanodon (Machairodus) primcevus. (Machairodus) occidentalis. Dinictis felina. Ruminantia. Oreodontidoe. Oreodon culbertsoni. gracilis. major, affiiiis. hybridus. bullatus. Merycochoorus proprma Leptauchenia major, decora, nitida. Agriochceridce. Agriochcerus antiquus. major, latifroiis. Camelidse. Poebrotherium wilsoui. Protomeryx halli. Mosehidae. Leptomeryx evansi. Artiodactyla. Suidae. Elotherium mortoni. Since this list was published numerous genera and species have been discovered in Wyoming and other districts in the far west from what appear to be the older or Eocene group of beds. Amongst these the most remarkable is the large Dinoceras mirabilis, an animal which had three pairs of horns, and which was intermediate in character between the Proboscideans and the Perissodactyles. There are also 1 Journ. Acad. Nat. Sci. Philadelphia, vol. vii. 1869. Artiodactyla. Suidao. Elotherium ingens. superbum. leidyauum. Perchcerus probus. Leptochcerus spectabilis. Nanohyus percinus. Anthracotheridce. Hyopotamus americauus. Anoplotheridse. Titanothcrium prouti. Perissodactyla. Rhinocerotidffi. Rhinoceros. Hyrocodon. Tapiridse. Lophiodon. Solidungula. Anchitheriidae. Anchitherium. Anchippus. Hypohippus. Parahippus. Anchippodus. Rodentia. Leporidre. Palffiolagus haydeni. Castoridfe. Palseocastor nebrascensis. Muridoe. Eumys elegans. Insectivora. Erinacidte. Leptictis haydeni. Ictops dakotensis. Omomys carteri. several generalised forms in the foregoing lists, which present a fauna with numerous remarkable features, which we can only briefly allude to. It is quite distinct in character from the present South American fauna, and yet, like it, it has a strong Asiatic facies ; at the same time it resembles in many points the older Tertiary fauna of Europe. The occurrence of rhinoceroses, camels, and musk-deer, is notice able ; but its great feature is the abundance of oreodonts (which family is not known elsewhere) and of equine forms. The Pliocene fauna consists of the following genera and species : Carnivora. Canidae. Canis saevus. temerarius. vafer. haydeni. Fclidae. Pseudselurus iutrepidus. yElurodon ferox. Ursidae. Leptarctus primus. Ruminantia. Oreodontidae. Merychyus elegans. medius. major. Camelidae. Procamelus robustus. occidentalis. gracilis. Homocamelus caninus. Megalomeryx niobrarensis. Merycodus necatus. Cervidae. Cervus warreni. Ruminantia. Antilopidse. Cosoryx furcatus. Artiodactyla. Suidse. Dicotyles. Perissodactyla. Rhinocerotidoe Rhinoceros. Proboscidese. Mastodon. Elephas. Solidungula. Equidae. Hipparion. Protohippus. Merychippus. Equus. Rodentia. Castoridre. Castor. Hystricidae. Hystrix. The Post-Pliocene forms are Carnivora. Canidse. Canis. Felidae. Felis. Ursidae. Procyon lotor. priscus. Ursus americanus amplidens. Arctodon pristinus. Mustelidse. Galera macrodon. Ruminantia. Camelidfe. Camelops kansanus. Cervidce. Cervus virginianus. canadensis. tarandus. americanus. Capridoe. Ovis mammillaris. Ovibos moschatus. bombifrons. cavifrons. Bovidae. Bison americanus. latifrons. antiquus. priscus. Artiodactyla. Suidse. Dicotyles nasutus. Platygonus compressus. Perissodactyla. Tapiridae. Perissodactyla. Proboscidean Mastodon. Elephas. Solidungula. Equidas. Hipparion venustum. Equus major. fraternus. pacificus. conversidena. tau. fossilis. Rodentia. Leporidae. Lepus sylvatica. Sciuridfe. Arctomys monax. Sciurus. Castoridte. Castor canadensis. Castoroides ohioensis, Cavidae. HydrochcErus ossopi. Chinchillidae. Amblyrhiza inundate Muridaj. Ncotorna magister. Marsupialia. Didelphys virginiana. Edentata. Megatherium mirabile. Megalonyx jeffersoni. dissimilis. validus. Megalocinus rodens. Ereptodon priscus. Mylodon harlani. Tapirus americanus. haysii. Here it is observable that, while this fauna has a general resemblance to that of the preceding period, most of the genera are distinct. Several existing genera make their appearance, as also a number of forms which appear to have
migrated from South America, and after a temporary estab-
