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 f 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. 481. 



