The Origin of Whales and Carnivores 195 
later steps of the transformation, by which the mastodons lost their 
lower tusks, and their relatively small and simple grinding teeth 
acquired the great size and highly complex structure of the true 
elephants, may be followed in the uppermost Miocene and Pliocene 
fossils of India and southern Europe. 
Egypt has also of late furnished some very welcome material 
which contributes to the solution of another unsolved problem which 
had quite eluded research, the origin of the whales. The toothed- 
whales may be traced back in several more or less parallel lines as 
far as the lower Miocene, but their predecessors in the Oligocene are 
still so incompletely known that safe conclusions can hardly be drawn 
from them. In the middle Eocene of Egypt, however, has been 
found a small, whale-like animal (Protocetus), which shows what 
the ancestral toothed-whale was like, and at the same time seems 
to connect these thoroughly marine mammals with land-animals. 
Though already entirely adapted to an aquatic mode of life, the 
teeth, skull and backbone of Protocetus display so many differences 
from those of the later whales and so many approximations to those 
of primitive, carnivorous land-mammals, as, in a large degree, to 
bridge over the gap between the two groups. Thus one of the most 
puzzling of palaeontological questions is in a fair way to receive a 
satisfactory answer. The origin of the whalebone-whales and their 
relations to the toothed-whales cannot yet be determined, since the 
necessary fossils have not been discovered. 
Among the carnivorous mammals, phylogenetic series are not so 
clear and distinct as among the hoofed animals, chiefly because the 
carnivores are individually much less abundant, and well-preserved 
skeletons are among the prizes of the collector. Nevertheless, much 
has already been learned concerning the mutual relations of the 
carnivorous families, and several phylogenetic series, notably that of 
the dogs, are quite complete. It has been made extremely probable 
that the primitive dogs of the Eocene represent the central stock, 
from which nearly or quite all the other families branched off, though 
the origin and descent of the cats have not yet been determined. 
It should be clearly understood that the foregoing account of 
mammalian descent is merely a selection of a few representative 
cases and might be almost indefinitely extended. Nothing has been 
said, for example, of the wonderful museum of ancient mammalian 
life which is entombed in the rocks of South America, especially of 
Patagonia, and which opens a world so entirely different from that of 
the northern continents, yet exemplifying the same laws of “descent 
with modification.” Very beautiful phylogenetic series have already 
been established among these most interesting and marvellously 
preserved fossils, but lack of space forbids a consideration of them. 
13—2 
