66 The American Geologist. Jan. i89i 
Pleistocene — the genera Moropus and Morotherlum of Marsh being re- 
jected from this order and referred to the (Jngulata. 
Like 1 1 » <-* Edentata, the cetaceans first occur in the Eocene but 
abounded in later eras. Their exact ancestry is at present unknown 
though there is little doubt that they have descended, as Flower has 
suggested, from forms resembling the present ungulates. The same 
author infers that they at first inhabited fresh-water, in as much as 
their remains have not been found in the Cretaceous rocks. All are now, 
however, marine. 
The sirenians also occur first in the Eocene, and have ever since •■been 
steadily dying out.'" To this result man has contributed by exterminat- 
ing the sea-cow of Behring's Island, about 120 years ago. Only one or 
two skeletons of this remarkable animal are now known in the museums 
of the world. The palaeontological importance of the Sirenia is small. 
The ungulates are palaeontological] y the most important of all the 
mammalian orders. Of the seven suborders, into which it is divided, only 
four contain living species. Of the three extinct suborders one Avnltly- 
poda — contains the huge Coryphodon of England, and North America, 
the Uintatherium of Wyoming, and some other similar forms. The pal- 
aeontology of one of its families — the Dinoecrata — affords a good illustra- 
tion of the fragmentary condition of the geological record. The author 
quotes the following from Prof. Marsh : 
'•The fossil remains of this group have hitherto been found in a 
single Eocene lake-basin in Wyoming, and none are known from any 
other part of this country, or of the Old World. These gigantic beasts 
which nearly equalled tin 1 elephant in size, roamed in great numbers 
about the ancient tropical lake in which many of them were entombed. " 
The suborder Condylarthra is also entirely extinct and was principally 
Eocene in age. Its most interesting member was Pheruwodus primcevus 
from the Lower Eocene of North America, an animal which Prof. Cope 
regards as the original type and probably the ancestor of all existing 
ungulates. 
Of the suborder Toxodtmtia all the species are also extinct. They 
were apparently intermediate between the Perissodacbyla, Proboscldea, 
and Rodentia. 
Two other of the suborders of the ungulates are apparently on the 
verge of extinction, the Hyracoidea which contains only two genera, 
and the Proboscldea which now has but two species. These latter — the 
elephants of India and Africa — alone on earth now represent the group 
which contains the well known fossils Dinotherium, Mastodon and 
Mammoth. 
To the two remaining suborders — the Art&odactyla and the Perisso- 
dactyla — belong the great majority living and extinct of this order and 
on them consequently the greatest interest and attention are concen- 
trated. It is needless to remark that the subject is treated with a full- 
ness and care which the great experience and learning of the author 
would lead us to expect. Space forbids anything like analysis and re- 
