1V 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 Natural 
History Classes in the Universities. 
To facilitate reference, and meet the most gener al 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 7m ctalics ; the writer’s own wishes coincide 
with those of the distinguished botanist Sir J. E. Suirn, 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.t 
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.{ 
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 
* Aj) the blundering and bad spelling of English and French genus-makers will be 
found carefully recorded in the “‘ Index Generum Malacozoorum,” by the accurate and 
\amented Dr. Herrmannsen, a work indispensable to every writer on Conchology. 
7 One example will suffice. In an “ Atheneum” report, by Prof. E. Forbes, 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 ! 
= The dates on the title pages of Journals and Transactions of Scientific Societies, 
are not usually dates of publication, but refer to the years for which they are issued to 
the subscribers. It is almost imposzit-e afterwarda to correct these false dates, 
