18 Biographical Memoir of 
in number, and confined to molluscs and zoophytes. In 
the older flétz rocks they are of more perfect animals; 
and in the newest flétz* and alluvial rocks, of birds and quad- 
rupeds, or animals of the most perfect kinds. . He also 
found that the oldest vegetable petrifactions were of marine 
plants, the newer of large trees. A careful study of the 
genera and species of petrifactions disclosed to him another 
important fact, viz., that the fossils contained in the old- 
est rocks are very different from any of the genera or spe- 
cies of the present time; that the newer the formation the 
more do the remains approach in form to the organic beings 
of the present creation, and that in the very newest for- 
mations fossil remains of the present existing species oc- 
cur. He also ascertained that the fossils in the oldest 
rocks were much more mineralised than the petrifactions 
in the newer rocks, and that in the newest rocks they were 
merely bleached or calcined. He found that some species 
of fossils were confined to particular beds, others were dis- 
tributed throughout whole formations, and others seemed 
to occur in several different formations ; the original species 
found in these formations appearing to have been so consti- 
tuted as to live through a variety of changes which had de- 
stroyed thousands of other species, which he found confined to 
particular beds. He ascertained the existence of fresh water 
shells in solid strata, sometimes alone, sometimes intermixed 
with marine productions. These highly interesting observa- 
tions having become generally known by means of his pupils, 
gave a stimulus to the study of fossils, which in a few years 
produced important results. They attracted the particular 
attention of the mineralogist, and roused the curiosity of the 
zoologist and botanist, who saw land before them,—a wide 
field of the most interesting nature. The mineralogist con- 
fidently anticipated from this study important elucidations in 
regard to the various changes the earth had undergone, dur- 
Sedgwick and Murchison mark the commencement of a new era in those geo- 
logical studies which relate to what had been called, until then, the Transition 
or Greywacke formation. Jameson was of opinion that the true Cambrian sys- 
tem existed highly developed in many parts of Scotland.—EpIrT. 
* In the district which Werner first investigated, the primitive and transi- 
tion strata were highly inclined, while the secondary of Lehman were hori- 
zontal. To these latter he (Lehman) gave the name of flitz.— EDIT. 
