206 CASE OF THE COS FOSSILS EXPLAINED. 



freshwater species, and destroy the latter al- 

 together. 



Such an explanation is consistent with what 

 we now know of the modes of variation among 

 fresh-water mollusca, and accounts sufficiently for 

 a very remarkable palasontological phenomenon, 

 which at first glance appeared to afford strong 

 support to the notion of a transmutation of 

 species in time. 



The preceding notes are offered as contribu- 

 tions towards the geology of Asia Minor. For 

 some years past the structure of western Asia 

 has furnished the subjects of several interesting 

 memoirs and notices. The most active and ac- 

 curate labourers in the field have been our 

 distinguished countrymen, Mr. W. J. Hamilton 

 and Mr. H. E. Strickland; their joint papers may 

 be found in the Transactions of the Geological 

 Society ; and in the valuable " Travels" of the 

 first-named gentleman, an interesting account of 

 the geology of the country in the line of his 

 journeys is given. In Mr. Ainsworth's Travels 

 are also many notices of the structure of the dis- 

 tricts he explored ; and Mr. Warrington Smyth 

 has lately (in the Quarterly Journal of the Geo- 



