The Value of Paleontology. 5 
lightened. This we find to be the case with birds and Dinosauria. 
’The lower bones of the pelvis with the contained organs are 
thrown backwards, while the fore-limbs are lightened and the 
head reduced in proportionate size. 
The parallelism of types with transient embryonic conditions of 
other types aids the paleontologist essentially in the classification 
or proper location of a specimen. Its relation to known series 
must be first determined, as this obviously precedes in reconstruc- 
tion all application of the law of uniformity. Such reference 
having been made either to a new series or to a place in a known 
series, the considerations heretofore adduced come into view, but 
not sooner. Hence the law of parallelism is as essential to the 
-paleontologist, as it is all-pervading and all-expressive of nature 
herself. 
II. 
Paleontology in its relation to Geology is a partially empirical 
science. Thus while its indications are definite for one locality, 
they have not identical significance for all localities on the earth’s 
surface. The lower we descend in the scale of being, the more 
uniform over great areas are its phenomena; but among higher 
animals, especially vertebrates, the greater the geographical pecu- 
liarities as compared with the stratigraphical. Prof. Agassiz once 
said that the existing geographical faune are more distinct than 
the extinct faunz of two consecutive epochs of geologic time, a 
statement justified by many facts. Hence it has been believed by 
some that fossil vertebrates cannot furnish conclusive evidence | 
of the age of the rock strata in which they occur. For, say they, 
we have to-day existing on the Australian continent, animals that 
approach more nearly to those found fossil in the Jurassic forma- 
tions of Europe than to any now living on the latter continent; so 
that were Australia to be presently submerged, and her strata and 
fossils again. brought to light, the paleontologist would assert that 
the sun had not shone on that land since the days of the Jura. And 
so he would were he not at the same time a zodlogist ; just as the. 
bare zodlogist would err in the opposite direction of assuming the 
modern age of the European Jurassic beds, because they contain 
the living types of Australia. Thus a foundation fact of zodlogy 
properly applied is essential to the paleontologist; namely, that 
the earth presents to-day four or more distinct faunal areas, the 
