IV PREFACE. 



duction of personal and peculiar views, and by adhering to 

 whatever was well established and sanctioned by the best 

 examples, to make the work suitable for the use of J^atural 

 History Classes in the Universities. 



To facilitate reference, and meet the most general require- 

 ments, the number of large groups and genera of shells has- 

 been restricted as much as possible, and those less important 

 or less understood, have been treated as " sub -genera." A 

 great many- duplicate and unnecessary names have been men- 

 tioned only, as will be seen by a glance at the Index, where 

 they are printed in italics ; the writer's own wishes coincide 

 with those of the distinguished botanist Sir J. E. SiiiTH, that 

 *'the system should not be encumbered with such names;" 

 but they have been admitted in deference to custom and 

 general opinion.^' 



The rules of the British Association, intended to secure 

 uniformity, have called into existence a few active opponents, 

 seeking to distinguish themselves by the employment of pre- 

 Linnean and MS. names, on the pretence of carrying out the 

 *' law of priority " (p. 48). But this folly has reached its 

 height, and will fall into contempt when it has lost its 

 novelty, f 



The investigation of dates is the most disheartening work 

 upon which the time of an author can be employed ; it is 

 never safe to take them second-hand, and even reference to 

 the original works is not always satisfactory. J 



Those portions of the work have been treated in most 

 detail which throw light on particular branches of anatomy 

 and physiology ; or on great natural history problems, such 



* All the blundering and bad spelling of English and Erench genus-makers will be 

 found carefully recorded in the " Index Generum Malacozoonun," bj^ the accurate and 

 \aiTLented Dr. Herrnaannsen, a work indispensable to every writer on Conchology. 



t One example will suffice. In an " Atheuseum " report, by Prof. E. Eorbes, the 

 name " Lottia fulva" was misprinted " Jothia fulva;" but although immediately 

 corrected, the erratum was formally installed as a " new genus," in the works of 

 Gray, Philippi, Catlow, Adams, and other conchologists ! 



X The dates on the title pages of Journals and Transactions of Scientific Societies, 

 are not usually dates of jncblication, but refer to the years /or ivhich they are issued to 

 the subscribers. It is almost impossible afterwards to correct these false dates. 



