30 Mr. Swainson on the Characters 
a considerable increase of new species, and a more perfect eluci- 
dation of many of the old ones; but, on the other hand, the same 
over-refinement which marks the characters of his genera, will be 
traced in the discrimination of his species; this is more particu 
larly the case in his account of the genera Conus, Oliva, and Helix. 
Let me not, however, be misunderstood, as wishing to depreciate 
the merits of this great man. His general reputation could not be 
affected either by my praise or my censure. But obliged, as he 
has been, to employ the sight of another in finishing his latter 
volumes, it would perhaps have been better for his own sake, and 
that of the science, to which he has devoted his long life and great 
abilities, ifthey had never been published. 
- The importance of monographs, or complete histories of parti- 
cular tribes, or families, in every branch of natural history is un- 
questionably very great; for their object is, not only to ascertain 
the limits'of genera, and the affinities and analogies, which the indi- 
viduals of such genera bear to others, but likewise to include the 
history of all the species thereunto belonging. To accomplish this, 
however, is in the power of a very few. Access must be had to the 
rich contents of foreign museums, and of costly libraries, to supply 
what may be deficient in minor collections; and it is from this 
cause that nearly all the monographs of extensive families have 
proceeded from naturalists in the charge of public museums, or in 
the possession of immense private collections. From the labours 
of these men science has received the. greatest assistance. But, 
although few can enjoy the advantages such materials afford, con- 
siderable benefits will be derived from the labours of those, who 
frame a correct diagnosis of individual species ; particularly when 
relative characters are subjoined, and comparisons made between 
others to which they bear a resemblance. When it is considered 
how many rare and unknown shells have lain for years in the cabi- 
nets of mere collectors, and how much greater is the number of 
those species more usually seen, but which are likewise unrecorded, 
the value of these isolated descriptions will be rightly understood. 
They are the indispensable materials for completing a general 
suryey of the natural world, and constitute the ultimate object of 
