378 AN INTRODUCTION TO THE STUDY OF FOSSILS 



Order i, Monotremata 



Principal characters given above under sub-class Prototheria. 

 Name from Greek monos, one, + trema, opening, in allusion to 



the cloaca. 



If we except the very small, primitive, and doubtfully mam- 

 malian Protodonta (e.g. Dromatherium) of the Upper Triassic 

 of North America, no remains of this order have with certainty 

 been found before the Pleistocene. The two living genera, — 

 duck bill (Ornithorhynchus) and the spiny anteater (Echidna) 

 are confined to the Australian region. 



Order 2, Marsupialia 



Chief characters given above under sub-class (2), the Meta- 

 theria. Name from Latin marsupium, a pouch, in allusion to 

 the ventral pouch for carrying the young. 



If we include here the possibly marsupial carnivorous sub-order 

 Triconodonta (Jurassic; including Triconodon and Phascolo- 

 therium) and the herbivorous, North American, European and 

 South African sub-order Multituberculata (Upper Triassic to 

 Eocene, including the Jurassic Plagiaulax and the Basal Eocene 

 Polymastodon) , this order is known from the Upper Triassic to 

 the present. The opossums, now confined to North and South 

 America, are known here probably since the Cretaceous and in 

 Europe during the Lower Tertiary. Except for the American 

 opossums and Caenolestes all marsupials are at present con- 

 fined to the Australian region ; they include the Tasmanian 

 wolf and bandicoots of the polyprotodonts, or marsupials with 

 many front teeth of equal size, and the kangaroos, wombats 

 and flying phalangers of the herbivorous diprotodonts, or mar- 

 supials with two enlarged incisors. Representatives of both 

 of these groups were living in South America during the Ter- 

 tiary. 



