182 On Aquatic Carnivorous Coleoptera or Dytiscide. 
“Species général des Coléoptéres—Hydrocanthares et Gyriniens.” The descriptions 
of this justly respected writer are very good, and may continue to be consulted with 
great advantage in respect to the shape, colour, sculpture, and similar specific 
characters of the 317 species known to him. A reference to each species described 
by Aubé in the work alluded to, as well as to the species subsequently described by 
various authors, will be found in the Munich Catalogue. I would also specially call 
attention to the work of Schiodte (Genera og Species af Danmarks Eleutherata”) 
published at Copenhagen in 1841, because six of its valuable plates consist of 
figures of structural details of these water beetles. 
The carnivorous water beetles are included in the second volume of the Munich 
Catalogue which was published in the year 1868, and in the period that has since 
elapsed several authors have given us works or notes relating to these creatures. 
Of such, Crotch “ Revision of the Dytiscidee of the United States,” (Ir. Amer. Ent. 
Soc. 1873), Sahlberg ‘‘Enumeratio Coleopterorum Carnivororum Fennize (Notiser 
ur Sillskapets pro Fauna et Flora Fennica Forhandligar, XIV, 1878), Regimbart 
Etude sur la classification des Dytiscidee (Ann. Soc. Ent. France 1878), and Bedel 
“Faune des Coleopterés du bassin de la Seine,” (published as a supplement to the Ann. 
Soc. Ent. France, 18S0,) deserve special notice, inasmuch as their works are of a 
systematic character, and contain a quantity of information arranged in such form 
that it may be easily consulted and used. 
Numerous entomologists and two museums have contributed to the completion 
of the work, by communicating to me either extensive collections, or a few rare and 
little known species. The Musée Royal d’Histoire Naturelle at Brussels, and the 
Museo Civico di Storia Naturale of Genoa have allowed their collections of this family 
to remain in my hands for a considerable period, and the Comte Henry de 
Bonvouloir of Paris has entrusted to me for several years the whole of his collections 
of Dytiscidee, comprising the larger part of Dejean’s original collection of the family, 
and many of the specimens actually described by Aubé, and for this assistance I 
offer him grateful acknowledgment. 
To Dr. Leconte, of Philadelphia, I am greatly indebted for the loan of a series of 
typical specimens of the species described and named by him in his numerous 
valuable entomological memoirs. Dr. Horn, of Philadelphia, M. Léon Fairmaire, of 
Paris, The Rev. A. Matthews, of Gumley, Leicestershire, Prof. Sahlberg, of 
Helsingfors, and Herr Ernst Wehncke, of Harburg on Elbe, have all loaned me 
speciinens of which I had need and for doing this I heartily thank them. I will 
also niention here that I adopted the plan of determining collections and specimens 
sent to me by means of a number attached to the species instead of a name; the 
number used by me for this purpose will be found attached to each species in the 
present work, and is placed after the description of the habitat in each case. 
The concluding part of this memoir is intended to be a contribution towards a 
natural classification of the species previously characterized. This classification I 
