xiv Proceedings of Royal Society of Edinburgh. 
labours in this and other fields. In all the later issues of this great 
work he shows the same astonishing knowledge of the literature of 
mineralogy. Side by side with this critical compilation of facts, 
however, we find abundant evidence of independent research and 
thought. He was at all times less interested in the study of indi- 
vidual mineral species than in the broader questions suggested by a 
review of the whole science — such as the classification of minerals, 
theories of crystallogeny, and the morphological relations of species. 
Mineralogy was his first love, but eventually it became displaced 
in his affections by its sister Geology. He found in this science 
greater scope for his activity. The interesting phenomena with 
which it dealt, and the many problems which it suggested, natur- 
ally fascinated a mind like his, and he turned from mineralogy, 
which he often spoke of as “ a department of limited ideas and 
principles,” to devote his best energies to geological investigation. 
His Manual of Geology , which has passed through four editions, 
has long been recognised by geologists in all countries as a masterly 
work. It not only sets forth, with admirable clearness, the facts of 
the science, but everywhere displays the critical acumen, the 
breadth of view, and originality of a truly philosophical mind. 
Dana was not only an active and persistent observer in the field, 
adding much to our knowledge of crystalline rocks and glacial 
phenomena, but a generaliser of the first order. Hence it is that 
we find him turning from first to last to such grand questions as 
the origin of continental areas and oceanic depressions, the problems 
of mountain-making, and the phenomena of volcanic action. We 
must remember also that the work he accomplished in Zoology was 
of great interest and importance. His extensive reports on the 
Zoophytes and the Crustacea, obtained during the Wilkes’ Expedi- 
tion, contain descriptions of upwards of 700 forms new to science, 
while his discussion of the relations of species, and his development 
of the classification, are held in the highest estimation by biologists. 
Dana began his zoological studies with a belief, then general, in 
the special creation of species. It was not until many years’ 
reflection that he came eventually to accept the principle of evolu- 
tion by natural variation. In the last edition of his Manual of 
Geology (1895), he writes : f ‘ It is perceived that the law of nature 
here exemplified is not ‘like produces like,’ but like ivith an incre - 
