xl AMERICAN FISHES. 
equipped by learning, intellectual capacity, or critical ability for success in 
such an undertaking. The result was that a large number of nominal 
species were, to a certain extent, “ established,” but there were not sufficient 
data for their correct determination. Many later naturalists, too, introduced 
“new species” without sufficient investigation. 
Meanwhile, methods of study and the aims of science were modified. An 
entirely unforeseen number of species was revealed by scientific travellers 
and expeditions. The limit of “near 500” species of fishes foretold by 
Ray had been passed long before the end of the eighteenth century, and 
over 12,000 had been made known before the end of the nineteenth. 
These immense numbers entailed a different conception of genera to receive 
them, and consequently the latter became more and more restricted. One 
of the unfortunate concomitants of the binominal nomenclature, which 
practically all later naturalists have adopted from Linnaus, was that a 
change of generic name was necessitated with each change from a generic 
concept. — 
Gradually specimens were obtained from the same localities as those 
which had served as the types of insufficient definitions, and such “ topo- 
types” enabled naturalists to restore many old names and necessitated the 
withdrawal of others that had become familiar through long usage; the 
re-examination of old types, including some of Linnzan species, had a like 
effect. The connection of such resurrected names with late generic terms 
naturally gave new specific compounds. 
The full recognition of the truth that Evolution had ever been active in 
the transmutation of old species into “new” compelled a different treat- 
ment of animals from the postulate which was formerly dominant,—that 
species were created such. More profound investigations were demanded, 
and it became the aim of science to group objects according to radical 
characteristics of their organization rather than to serve the convenience of 
an identifier of species. Classification is now a device by the best informed 
for the expression in nomenclature of the facts educed from comparative 
anatomy. The aim is to express by the different group names—species, 
genera, family, order, etc.—the relative degrees of affinity, the manner in 
which they have diverged from common ancestors, and the extent of the 
gaps between the various groups. Of course there must arise and exist 
differences of opinion as to such questions, and the different classifications 
are the expressions of such differences. Those differences are many, but 
they are, slowly but surely, becoming fewer in the course of time. 
