PREFACE 



This Manual, which for six years has occupied the writer's 

 unceasing attention, was intended as a companion to Col. 

 Portlock's Geology ; and the desire to make it worthy of that 

 association has led to an amount of labour and expense which 

 only a very extended circulation will repay. 



The plan and title have been taken from the "Manuel des 

 MoUusques" of M. Sander Eang, (1 8 2 9j— incomparably the 

 best work of its kind— for an acquaintance with which the writer 

 was indebted, sixteen years ago, to his friend and master, 

 William Lonsdale— the founder of the " Devonian System '' 

 in Geology. 



On the subject of classification and nomenclature he has 

 followed the advice and example of his former colleague in the 

 Geological Society, the late Prof. Edward Forres's ; without 

 whose approval he has seldom added to, or deviated from, the 

 practice and plan of the " History of British Mollusca." 



That he was right in taking this course, he has now the sanc- 

 tion of the highest authority in this country for believing ;— since 

 the same scheme has been employed by Prof. Owen in the 

 Hunterian Lectures and Catalogue. It has also been adopted by 

 Br. E. Balfour in the Madras Museum; by the Key. Prof 

 Henslow, in his Report to the British Association on the 

 Formation of Typical Collections; and by Prof. Morris in 

 his Catalogue of British Fossils. 



It was the writer's desire, by abstaining from the introduc- 

 tion of personal and peculiar views, and by adhering to whatever 

 was well established and sanctioned by the best examples to 



