139 
Journal; and an analysis of the coprolites in the forty-eighth 
volume. He described two more species in the fourth vol- 
ume of the new series of the Journal, still more in the 
twenty-first volume. His first quarto volume on the Fossil 
Footmarks of the United States, from the Transactions of 
the American Academy, appeared in 1848, and additional 
facts respecting the Otozoum Moodii in the Proceedings of the 
Association for 1855. His quarto report on the Ichnology 
of New England appeared in 1858, with further remarks, 
in the Proceedings of the Association for 1860, and new facts 
and conclusions in the Journal for 1863. These are his 
monuments. Most men would consider them sufficient for 
one life. In his they merely mark an episode; but there 
were others: an episode only of his scientific life. I leave 
the notice of it here, with the remark that he worked in it 
almost alone, and that he has left it standing unaltered by 
the labors of others. His publications on this theme are 
not only classical, but standard. His determinations are of 
accepted authority, which no controversial doubts as yet ob- 
scure. I pass now to others of which this cannot be said, — 
in which he has been a disciple rather than a master, — and 
which are rather characteristic of the genius of the geolo- 
gist, than influential in the progress of geology. 
I refer first to the study of the Drift. In Structural 
Geology this is the great question of the day. The subject 
has extraordinary difficulties. Could we determine the 
cause of the drift deposits, it would explain much that is 
puzzling in all the formations, down to the very base of the 
Laurentian. The wildest speculations meet at this point of 
Geology. It is the horse-latitudes of the voyage. Forty 
years ago the Swiss geologists shocked the world with the 
announcement that all the giant blocks of primary rock 
which travellers see lying stranded half-way up the Jura 
