54 MAIOJAL OF THE MOLLUSCA. 



boldt ; FaLricius and Latreille have divided the world into > 

 climatal Insect-provinces ; and Professor E. Forbes has con- 

 stmcted a map of the homoiozoic helts or zones of marine life. 

 To all these the remark of Mr. Kirby is applicable — that any 

 division of the globe into provinces, by means of equivalent 

 parallels and meridians, wears the appearance of an artificial 

 and arbitrary system, rather than of one according to nature. 

 Professor Forbes has been careful to point out that although 

 the V Faunas of regions under similar physical conditions bear 

 a striking resemblance to each other" — this resemblance is 

 produced, ' ' not by identity of species, or even of genera, but 

 by representation " (p. 45). 



Origin of the Natural History Provinces. Mr. Kirby appears 

 to have been the first to recognise the truth that physical 

 conditions were not the primary causes of the zoological pro- 

 vinces, which he ' ' regarded as fixed by the will of the Creator, 

 rather than as regulated by isothermal lines." * Mr. Swainson 

 also has shown that the ' ' circumstances connected with tem- 

 perature, food, situation, and foes, are totally insufficient to 

 account for the phenomena of animal geography," which he 

 attributes to the operation of unknown laws.f 



The most important contribution towards a knowledge of 

 these " unknown laws " has been made by Professor E. Forbes, 

 who was perhaps the first naturalist ever in a position to avail 

 himself of the great storehouse of facts accumulated by geolo- 

 gists, respecting the distribution of organic life in ' ' the former 

 world." This subject will be referred to again in connection 

 with the subject of Fossil Shells ; meanwhile it may be stated 

 that, according to this evidence, the Faunas of the Provinces 

 are of various ages, and that their origin is connected with 

 former (often very remote) geological changes, and a difierent 

 distribution of land and water over the surface of the globe. 



MAEINE PHOYINCES. 



Amongst the genera of marine shells there are some which 

 have been considered particularly indicative of climate. From 

 the Arctic list the following may be taken as examples of the 

 shells of high latitudes ; those marked * being found in the 

 southern as well as in the northern hemisphere : — 



• Introduction to Entomologj'. 



t Treatise on Geography and Classification of Animals, Lardner's Cabinet Cyclo* 

 psedia. 



