Prof. K. A. von Zittel—On the Mammata. 511 
poorer in species than that of Europe; it has, moreover, been less 
studied, and at times it is difficult to separate it from that of the 
older Hquus-beds. As characteristic species may be mentioned, 
Mastodon Americanus, Cervus alces, Cervalces Americanus, Rangifer 
tarandus, ? Cervus Canadensis, Bos Americanus, Ovibos bombifrons, 
Canis-lupus, Ursus ferox, ? Felis atrox. Noteworthy is the absence 
of Hguus, Rhinoceros, Hippopotamus, Dicotyles, Sus, Machairodus, 
Ursus speleus, Felis spelea, Hyena spelea, Bison priscus, Bos prim- 
genius, Cervus elaphus, capreolus, eurycerus, and a great number of 
other forms abundant in Hurope and Northern Asia. The Diluvial 
Mammalian fauna of North America stands in precisely the same 
relation to that of Hurope as the existing faunas of the two continents, 
bear to each other. Identical species are extremely rare; on the 
other hand the general character is similar, and points to a 
common origin. 
In South Asia and South America the Diluvial faunas succeeding 
those of the Tertiary period consist for the main part of species still 
existing, but they show somewhat closer ties to their Tertiary fore- 
runners. 
From the whole history of Mammalian development, from the 
Trias to the present time, it becomes definitely evident, in spite of 
all the deficiencies in the Paleontological record, that the genetical 
connection between particular faunas, notwithstanding manifold 
interruptions from geological events, was never completely broken, 
and that each particular assemblage of animals has been produced 
by the gradual transformation of its elements from an earlier pre- 
ceding one, and at the same time it has yielded the seed for that 
next succeeding. Certain genera (Didelphys, Sciurus, Myoxus, Sorex) 
belonging to the micro-fauna can be traced back into the Hocene, 
and they have indeed produced new species since their first appear- 
ance, but have experienced no transformation worth mentioning, 
as also the Polyprotodont Marsupials, Insectivora and Rodents, 
which represent generally the least changeable types of Mammalia. 
Recent genera of more considerable size make their appearance in 
constantly increasing numbers from the Lower Miocene onwards, 
and they partly continue up to the present day. 
Our entire animal and plant environment is incontestably rooted 
in former periods, and in no class of animals does the intimate con- 
nection between the past and the present stand out sharper to vue 
view than in the Mammalia. 
Concerning their origin and earliest distribution in Mesozoic time 
there is still wanting, unfortunately, satisfactory information, but 
the uniformity of the Jurassic Mammalian faunas in Hurope and 
North America, which consist of Allotheria and Polyprotodont 
Marsupials (or primitive, perhaps marsupial, Insectivora); the 
appearance of a typical Allotherian genus in the South African 
Trias; and the great resemblance of the Upper Cretaceous genera to 
their Jurassic forerunners, make it extremely probable that in the 
Mesozoic period a single uniform Mammalian fauna peopled Europe 
