Pe PACE 
The latter part of the nineteenth century was an 
important period for the science of Conchology. While 
many private collectors were gathering specimens of all 
kinds, and incidentally making many new discoveries, 
the universities were establishing seaside laboratories, 
the Government was sending out exploring vessels, the 
learned societies were putting forth publications, and 
especially the National Museum at Washington was issu- 
ing very valuable bulletins, embodying the conclusions 
of its painstaking investigators. 
This activity has resulted in the accumulation of much 
new material, and incidentally the changing of many old 
names. The latter work is an ungracious piece of busi- 
ness at best, and has seldom been indulged in wantonly. 
But new views on the subject of classification, and an 
enlarged knowledge of the fossil progenitors of existing 
species, have compelled the readjustment of what before 
seemed settled. It is comparatively easy, when collecting 
in a small field, to separate the specimens into fixed and 
definite groups; but as one’s observations become 
extended, the varieties multiply, and increasing knowl- 
edge of both facts and records causes embarrassment. 
The necessary changes, however, even of familiar names, 
must not be too deeply regretted, for they indicate a 
real advance in our conception of the great plan of 
nature. 
The kind reception given to my previous efforts to 
popularize the study of mollusks, together with the 
