470 TRANSACTIONS OF SECTION GC. 
nearly complete skeletons in the north of Russia that we are likely soon 
to learn more about them from this European country than from the South 
African area itself. Quite lately I have received numerous bones from a 
red marl in Rio Grande do Sul, Southern Brazil, which show that not merely 
Anomodonts, but also other characteristic Triassic land reptiles were likewise 
abundant in that region. We are therefore now embarrassed by the richness 
of the sources whence we may obtain the ancestors of mammals. Whereas 
some years ago it appeared sufficient to search South Africa for the solution 
of the problem, we are now uncertain in which direction to turn. We are 
still perhaps inclined to favour the South African source; but this is 
only because we know nothing of the Jurassic land animals of that part of 
the world, and we cherish a lingering hope that they may eventually 
prove to have included the early mammals for which we have so long sought 
in vain. 
The mystery of the origin of the marine mammals of the order Sirenia 
and Cetacea appears to have been diminished by the discoveries of the 
Geological Survey of Egypt, Dr. Andrews, and Dr. Fraas in the Eocene 
and Oligocene deposits of the Mokattam Hills and the Fayum. It is now 
clear that the Sirenians are closely related to the small primitive ancestors 
of the elephants ; while, so far as the skull and dentition are concerned, we 
know nearly all the links between the early toothed whales (or Zeuglodonts) 
and the primitive ancestors of the Carnivora (or Creodonts). The most primi- 
tive form of Sirenian skull hitherto discovered, however, is not trom Egypt, 
but from the other side of the world, Jamaica; and exactly the same 
Zeuglodonts, even with an associated sea-snake, occur so far away from 
Egypt as Alabama, U.S.A. The problem of the precise origin of these 
marine mammals is therefore not so simple as it would have appeared 
to be had we known only the Egyptian fossils. The progress of discovery, 
while revealing many most important generalities, has made it impossible 
to vouch for the accuracy of the details in any ‘ genealogical tree.’ 
Another difficulty resulting from the latest systematic researches is sug- 
gested by the extinct hoofed mammals of South America. The llamas, deer, 
and peccaries existing in South America at the present time are all immi- 
grants from the northern continent ; but during the greater part of the 
Tertiary period there lived in that country a large number of indigenous 
hoofed mammals, which originated quite independently of those in other 
regions. They seem to have begun in early Eocene times much in the same 
manner as those of the northern hemisphere ; but as they became gradually 
adapted for life on hard ground, they formed groups which are very different 
from those with which we are familiar in our part of the world. Some of 
them (Proterotheriidz) were one-toed mimics of the horses, but without the 
advanced type of brain, the deepened grinding teeth, the mobile neck, or the 
really effective wrist and ankle. Others (Toxodontides) made some approach 
towards rhinoceroses in shape and habit, even with a-trace of a horn on the 
nose. Until their independent origin was demonstrated, these curious 
animals could not be understood ; and it is probable that there are innumer- 
able similar cases of parallel development of groups, by which in our 
ignorance we are often misled. 
It would be easy to multiply instances, but I think I have now said 
enough to show that every advance in the study of fossils reveals more 
problems than it solves. During the last two decades the progress in our 
knowledge of the extinct backboned animals has been truly astonishing, 
thanks especially to the great explorations in North America, Patagonia, 
Egypt, Madagascar, and South Africa. Whole groups have been traced a 
long way towards their origin ; but with them have been found a number 
of previously unknown groups ‘which complicate all questions of evolution 
to an almost bewildering extent. Animals formerly known only by frag- 
ments are now represented by nearly complete skeletons, and several which 
