pate our 26, oe derived from all these different 
126 . _ Scientific Intelligence. 
There is another field of investigation hardly yet entered upon, which — 
is likely to — largely to the improvement of our classification, 
I refer to the study of fossils, compared in their —_ feculeeaae 
_ the — of their living ee aslenk — been 
period, and also what is the oe of affinity they have to the lower 
types_of their respective classe 
I would mention, in this Reis the necessity of a revised com- 
parison of the Trilobites, With the earliest stages of development of 
Crustacea, when it will be found, as I have already seen it, that almost 
all the genera of Trilobites seem to be the prophetic ima 
genus, its appropriate ran venture even to say an the “time will 
come when the relative age 2 of fossils, within eertain limits, will be as 
satisfactory a ide | in assigning them their normal position in a natural 
system, as the facts derived from the study of their structure,—so inti 
mate are the oe existing between all parts of the wonderful 
plan displayed in cre 
ittle or no adenine ps as yet been derived from the study of the 
relations of animals with the elements in which they live, in ascertain- — 
ing = natural relations among themselves; but even in this respect 
we derive valuable hints from a careful study of the geographical 
disteibantion of all animals; and the mere nature of the elements in 
ich they live naturally. 
Oar reviewing lately the whole animal kingdom, with a view to ascer- 
tain what is. the value of the natural connection between the animals 
er guide, 
iui fabeeatia reapectng their natural seam may be fairly derived from 
their ae of 
It w he che. us that as soon as we introduce simultaneously 
rees; a8 soon as we allow the embryonic development, geolog! 
succession, geographical disttthunion, and relation to the natural — 
us in our efforts to assign to all animals a natural | 
ies ia one cal system, we shall be able to sketch a far more com 
