The Queensland Naturalist October, 1930 
S4 
e.g., the lamellibranchs and the gastropods the methods 
have hardly yet been applied. 
Perhaps, from the point of view of a worker in this 
country, the most marked change wrought by modern 
methods lias been in generic nomenclature. Under the 
older methods most genera included a very large number 
of species. While many such genera undoubtedly are of 
monophvletic origin it has been shown repeatedly that 
the group of species constituting a ‘/genus” really often 
represented a collection of subsidiary groups of widely 
different origin (as e.g. in ‘ ‘ Cyathophyllum ’ ’) or else (as 
in “Prcductus”) such species were naturally grouped 
into smaller assemblages of related forms which well 
could be separated one from another, and defined as 
separate genera. The old, large, unwieldly genera usually 
were of little- value for correlation. By their aid it was 
usually possible to fix a fauna in its proper period, or 
perhaps to narrow it to the early, middle, or late portion 
of that period. But for more precise correlation such 
“genera” usually were useless. As a result, in correlat- 
ing the faunas of a country such as this, so far removed 
from the standard sections of Europe and America, more 
reliance usually was placed upon species. Such methods, 
however, lead to many inexact determinations. European 
species have been recorded very frequently from the 
Australian faunas ; but frequently such a name as applied 
in Australia, covers a large section of the group to which 
the original species belongs and not merely the species 
itself. As example of such usage one may quote the 
records in Australia of Spirifer disjunctus and Productus 
semireticulatus — in the former records the “species” 
really includes a number of forms of the genus, 
Cyrtospirifer, to which the original S. disjunctus belongs, 
while the so-called “Prcductus semireticulatus ” in Aus- 
tralia is really a suite of species of the genus Productus 
(sensu stricto). 
No one recognised more keenly than Etheridge the 
importance of correlation by species groups rather than 
bv species. But, under the older methods, when such 
groups were not specially defined, correlation by these 
methods was virtually impossible — for necessarily it 
involved a detailed investigation of the groups within 
every genus concerned. Modern phylogenetic work, 
although it lias caused a multiplication of generic names 
bewildering to- all but the specialist, is making the cor- 
relative work in distant countries very much easier, in 
