848 The American Naturalist. [October, 
various cetaceans. In 1868 he began the collection and inves- 
tigation of the fossil mammals of the western territory, and 
thenceforward devoted the larger share of his attention to the 
description and restoration of the numerous new species which 
he from time to time brought to light. The previous investi- 
gators of the extinct mammals of America had almost exclu- 
sively confined themselves to descriptions and illustrations of 
the crania and dentition, but a new era was introduced when 
Marsh and Cope sent out exploring expeditions or themselves 
collected. No parts of skeleton were neglected ; all were col- 
lected. Gradually the numerous bones from different parts of 
the skeleton were identified, and finally many of the beasts of 
old were resurrected into skeletons almost as complete as those 
just divested of muscles. 
The discoveries resulting from such thorough work quite 
modified or even overturned old conceptions. It became evi- 
dent that there was a great contrast between the development 
“of the mammals and that of the invertebrates, and even, 
though in a less degree, of fishes. It appeared that there was 
a much more rapid process of evolution for the mammals than 
for the lower classes. All the mammals of the oldest of the 
Tertiary periods were strange and very unlike those of recent 
times, and no descendants of even the same families lived to 
be the contemporaries of civilized man. The views of the 
founder of vertebrate paleontology were also to a considerable 
extent subverted. Cuvier taught that there was always a co- 
-ordination between the various systems of the animal frame 
and that from the remains or impress of one part the approx- 
imate structure of the other parts could be inferred. He even 
pushed this doctrine to such an extreme that he overlooked 
some obvious counter facts, One such case is so remarkable 
because it originated with Cuvier and was endorsed by Hux- 
ley” that it is worthy of mention here, and Huxley’s introduc- 
tion to it and translation of it may.be given. Huxley himself 
protests against the too literal application of Cuvier’s law, and 
‘recalls Cuvier’s own reserve: 
2 Huxley: ‘Introduction to the Classification of Animals,” 1869, in first chap- 
iter “On Classification in General.” 
