Address of John L. LeConte. 247 
approximation of allied forms, and the elimination of doubtful 
ones, must be accumulated ; and in the case of such perishable 
objects as those we are now dealing with, must be placed 
where they can have the protecting influences both of climate 
and personal care. 
At the same time, for ae Leia 254 the study of insects 
is peculiarly suitable; not only on account of the small size, 
ease of collecting, and little cost of pacar, the specimens, 
but because, from their varied mode of life in different stages 
of development, and perhaps for ie reasons, the species are 
less likely to be destroyed in the progress of geological 
changes, (For a fuller ae of these causes and of sev- 
eral other subjects which are briefly mentioned in this address, 
the reader may consult an excellent memoir by my learned 
friend, Mr. An \drew Murraye< ‘On the Genesaphical ‘Relations 
rve and pupe to other neighboring lands. However that 
may be, I have given you some grounds for believing as 
many of the species of insects now ‘living existed in the 
form before the ApRONERHOG of any living genera of mamm ei 
and we may su e that their unchanged descendants will 
probably survive he pone mammalian fauna, including our 
own rac 
I may add, moreover, that some poe tk RS in ns 
Rhynchophora, which, as I have said ab 
the earliest introduced of the Coleoptera, ashi with pees 
and definite limits, and clearly defined specific characters, so 
many generic modifications that I am compelled to think that 
we have in them an example of long sought unbroken series 
extending, in this instance, from early Mesozoic to the present 
time, and of which very few forms have become extinct. 
I have used the word species so often that yen will doubt- 
less be inclined to ask, what, then, is understood by a species ? 
Alas! I can tell you no more than has been told recently by 
many others. It is an assemblage of eardaele which differ 
from each other by very small or trifling and inconstant char- 
acters, of much less value than those in which they differ from 
any other asse assemblage of individuals. Who determines the 
value of these characters? The experienced student of that 
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