On Aquatic Carnivorous CoIeo2)tera or Di/tiscid(c. 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 Linneean 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 I am 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 w^ork. 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 attachedto zoological descriptions 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, neghgence, or haste. We possess already in 

 the Munich Catalogue of Coleoptera a 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 have described species belonging to it : both of these can be gathered from the 

 pages of the Munich Catalogue. The earlier descriptions are scattered in the pages 

 of zoological and entomological works from Linnseus till the time of Aub^ ; special 

 reference is due to the work of the last named author, who in 1S38 published the 



3 B 3 



