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Natural History of the United States. 211 
Mor groups, but yet, when so, these earliest forms were not gen- 
; as the expansion of the type after- 
ward took place through new creations, there were downward 
steps as ite as upward, though the upward were eminently the 
to the higher; in all cases, it brought out a purer development 
of the type and a fuller exhibition of its various capacities. 
I he fact of progress is none the less true under such a system. 
's actual law is daily receiving new illustrations from geological 
discoveries and becoming gradually intelligible to us in its va- 
. A hope, which some seem to have, that new facts 
will throw despite on all general views, is of shallow growth. 
one need fear that nature will ever prove her own lawlessness. 
€lmportant principles connected with this system of pro- 
ox brought out by Prof. Agassiz, are as follows :— 
IRST, ss parallelism between the geological succession of animals 
and: the embryonic growth of their living representatives.” The 
: The investigations of Miller upon the larve of all the families of 
Ming Asterioid beet d these .comparisons to 
ae sa ble us to exten se ,comp 
the igh nd Echinoids ena tee cbeigivde 
her Echinoderms also. The first point which 
