12 ON THE GEOGRAPHY OF ANIMALS. 
eighteen instances out of twenty, instantly recognise the 
butterflies of Africa from those of America? or what 
ornithologist would now confound the flycatchers or 
the warblers of the Old with those of the New World ? 
These are all indications of those primary and com- 
prehensive divisions, which both Fabricius and Latreille 
have lost sight of from a wish of attaining precision, 
and of entering upon details: they have, consequently, 
produced theories substantially built upon climate and 
temperature. M. Latreille, indeed, would seem to be 
fully aware of the slender foundation of all such specu- 
lations, since he remarks, with great truth, that as places 
where the temperature is the same, have different 
animals, it is impossible, in the actual state of our know- 
ledge, to fix these distinctions of climates upon a solid 
basis. This opinion, it appears, is entertained both by 
M. Humboldt and Mr. M‘Leay : and Mr. Kirby joins in 
believing, “‘that the real insect climates, or those in which 
certain groups or species appear, may be regarded as 
fixed by the will of the Creator, rather than as regu- 
lated by isothermal lines.” * It cannot for a moment be 
supposed, that the geographic distribution of insects is 
regulated by other laws than those which affect animals 
in general ; although each may possess some few pecu- 
liarities in their minor details: the above objections, 
therefore, although more especially urged against the 
two entomological theories we have here noticed, are no 
less applicable to all others, intending to trace the phe- 
nomena of animal geography to temperature; and to 
fix their natural provinces or climates by degrees of 
longitude or latitude. 
(17.) There yet remains to be noticed another hypo- 
thesis, more recently proposed, not, indeed, by a na- 
turalist, but by one whose physiological researches are 
of the highest value, and whose opinions, therefore, 
merit every attention. Dr. Prichard is the first who 
* Int. to Entom. vol, iv. p. 484, 
