IV rilEFACE. 



cluction 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 ISTatural 

 History Classes in the Universities. 



To facilitate reference, and meet the most general require- 

 ments, the number of large groups* and gdbcra of shells has 

 been restricted as much as possible, send 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. Smith, 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 Eritish 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 j)riority " (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 

 ne-ver safe to take them second-hand, and even reference to 

 the original works is not always satisfactory.^ 



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 tlie blundering and bad spelling of English and French genus-makers will be 

 found carefully recorded in the " Index Generum Malacozoorum," bj' the accurate and 

 \amented Dr. Herrmannsen, a work indispensable to everj' writer on Conchologj\ 



I One example will suffice. In an " Athenjeum " report, by Prof. E. Forbes, the 

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

 coiTCcted, 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 fuhlication, but refer to the years /or which they are issued to 

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



