On Aquatic Carnivorous Coleoptera or Dytiscide. 181 
Eleven hundred and seventy-one species are distinguished, in a more or less 
imperfect manner; and in addition to these there are recorded in the Munich 
catalogue of Coleoptera or in recently published works some three hundred or more 
names, a considerable proportion of which probably represent species unknown to 
me. As these descriptions are extremely scattered in works in various languages, 
and frequently rare or difficult of access, they are reprinted for the convenience of 
future workers (vide page 649). 
In the nomenclature of the species I have used the system of priority as set forth 
in my pamphlet on the object and method of zoological nomenclature. I treat the 
two words forming the name of each species as being practically one, and retain 
them unaltered, thus for the present abandoning the Linnean idea of making the 
name of a species indicate its position in classification. The arguments I have used 
in the paper referred to have not, so far as Iam aware, been answered ; and further 
reflection on the subject has convinced me that the system is not only logically con- 
sistent, but is likely to be practically useful, and capable of serving as a permanent 
basis for a system of synthetical classification. 
A large and constantly increasing portion of the space of descriptive zoological 
works is occupied by lists of synonyms: this burden is already so great that it has 
become a serious question whether zoologists can reduce the extent of these 
synonyms without danger to the precision and continuity of their work. The plan 
I have adopted of retaining as the name of the species, the original name, will serve 
the purpose of limiting future increase of synonyms ; for a very large proportion of 
those usually attached to zoologicaldescriptions consists in following the classificatory 
changes in the name of the species that inevitably result from the unfortunate 
method of making the name of the species dependent on that of the genus. Another 
aid is the relegation of pure synonyms (that is such as are not resultant from 
classification changes but from sheer error or accident) to catalogues published apart 
from descriptive works, where these synonyms may be recorded once and for all 
and then done with ; a catalogue should in fact serve as the place of final interment 
of these unfortunate results of accident, negligence, or haste. We possess already in 
the Munich Catalogue of Coleopteraa work in which a large proportion of synonyms 
are well recorded, and I have considered the existence of this valuable production 
sufficient reason for omitting the synonymy already recorded therein, and have 
contented myself with citing in the alphabetical index of this work such names as 
are necessary to establish a harmony between it and the catalogue in question. 
For a similar reason it forms no part of my plan to give a history of the previous 
and present condition of the taxonomy of the family, nor a list of all the writers 
who haye described species belonging to it: both of these can be gathered from the 
pages of the Munich Catalogue. The earlier descriptions are scattered im the pages 
of zoological and entomological works from Linnzeus till the time of Aubé; special 
reference is due to the work of the last named author, who in 1838 published the 
. 2B2 
