i] HISTORICAL 5 



it suffered from the mysticism of the author's ' quinary 

 system.' Ch. Ly ell's Principles of Geology should 

 have marked a new epoch, since in his Elements he 

 treats of the past history of the globe and the dis- 

 tribution of animals in time, and in his Principles 

 of their distribution in space in connexion with the 

 actual changes undergone by the surface of the 

 world. But as he restricted himself to the com- 

 paratively minor modern changes, and believed in 

 the permanency of the great oceans, he did after all 

 advance our problems but little. Meanwhile E. Forbes 

 of Edinburgh devoted himself to the marine fauna, 

 especially the Mollusca. He established nine ' homo- 

 zoic zones/ subdivided into 25 'provinces' based 

 chiefly on the isotherms or belts of equal temperature. 

 J. D. Dana of JS^ew Haven taking mainly the Crus- 

 tacea as a basis, and as leading factors the mean 

 temperatures of the coldest and of the warmest 

 months, arrived at five latitudinal zones, with many 

 provinces. In 1853 L. K. Schmarda of Vienna pub- 

 lished his two volumes comprising the distribution 

 of the whole animal kingdom. After devoting many 

 chapters to the possible physical causes and modes 

 of dispersal from original centres of creation, he 

 divided the land into 25 'realms,' some of which 

 were well selected, but they were obviously too 

 numerous for general purposes. This drawback was 

 overcome in 1857 by P. L. Sclater with the now 



