1 82 On Aquatic Carnivorous Coleoptera or Dytiscidae. 



" Species gcndral des Colcopteres — Hydi-ocanthares 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 Aube 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 186 8, 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 Dytiscidje of the United States," (Tr. Amer. Ent. 

 Soc. 1873), Sahlberg "Enumeratio Coleopterorum Carnivororum Fennise (Notiser 

 ur Siillskapets pro Fauna et Flora Fennica Forhandligar, XIV, 1873), Regimbart 

 Etude sur la classification des Dytiscidse (Ann. Soc. Ent. France 1878), and Bedel 

 " Faune des Coleoptercs du bassin de la Seine," (published as a supplement to the Ann. 

 Soc. Ent. France, IS SO,) deserve special notice, inasmuch as their works are of a 

 systematic character, and contain a ([uantity 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 Musee 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 Dytiscidoe, comprising the larger part of Dejean's original collection of the family, 

 and many of the specimens actually described by Aube, and for this assistance I 

 offer him grateful acknowledgment. 



To Dr. Lcconte, of Philadelpliia, 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. Leon 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 nie 

 specimens of which I had need and for doing this I heartily thank them. I will 

 also mention here that I adopted the plan of determining collections and specimens 

 sent to n)e 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 

 prestnt 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 



