Ixxxii INTRODUCTION. [CH. 



lusca in the European seas, many theories have been 

 from time to time advanced, each of which would divide 

 this great area into several distinct parts, or what are 

 called "provinces/' Professor Milne -Edwards, in the 

 ' Annales des Sciences Naturelles' for 1838, proposed 

 the following division — 1. Scandinavian, 2. Celtic, 3. 

 Mediterranean. Mr. S. P. Woodward, in his verv useful 

 little treatise, entitled ' Manual of the Mollusca ' (the 

 last edition of which was published in 1856), considered 

 that there are four provinces, viz. 1. Arctic, 2. Boreal, 

 3. Celtic, 4. Lusitanian; and these, according to this 

 writer, were "framed upon the widest possible basis.'' 

 In a posthumous work of the late Professor Edward 

 Forbes, which was most ably continued and edited by 

 Mr. Godwin- Austen in 1859, under the title of ' The 

 Natural History of the European Seas,' a fifth province 

 (the "Mediterranean") has been added to those above 

 enumerated. The latter scheme of distribution has been 

 recently adopted by Mr. M ^Andrew in the ^ Annals of 

 Natural History' for December 1861. 



Now, although such a division into "provinces" or 

 separate areas of distribution is very plausible, and pos- 

 sibly may be maintainable in the same sense as the divi- 

 sion of Mankind into distinct races, a definite principle 

 seems to be wanting in their construction. If we com- 

 pare any one of these schemes with another, a very 

 material discrepancy is observable as to the relative 

 limits of the proAdnces. For instance (not to travel far 

 from home), Milne-Edwards considered that the Celtic 

 province had its southern boundary in the Straits of 

 Gibraltar ; Woodward restricted the same limit of this 

 province to our own coasts ; while Forbes advocated its 

 extension " from the Bay of Biscay to the Baltic Sea." 



The principle of definition, as well as of construction. 



