Sept., 1912.] Matheson : Haliplid^ of North America. 157 



Skand. Col., I, 1859, p. 11; II, i860, p. 2. 1868. Dytiscidae, Gruppe Hali- 

 plini, Schaum, Kiesw. Naturg. Ins. Deutsch., I, 2, 9. 1873. Dytiscidae, Sub- 

 family Halipiides, Crotch, G. R., Trans. Amer. Ent. Soc, IV, p. 383. 

 1878. Dytiscidae, Tribus Haliplinae Regimbart, Ann. Soc. Ent. Fr., VIII 

 (s), p. 449. 1881. Haliplidae, Bedel, Fn. Col. Bass. Seine, I, p. 2, 219. 

 1881. Haliplidae, Horn, Trans. Amer. Ent. Soc, IX, p. 94. 1883. Hali- 

 plidae, Leconte and Horn, Classification Coleoptera North America, p. 60. 

 Dystiscidae, Subfamily Haliplini Seidl, Best. 19. 1885. Haliplidae, C. 

 Van den Branden, Catalogues des Coleopteres carnassiers aquatiques, 

 Ann. Soc. Ent. Belg., pp. 7-12. 1892. Haliplidae, Ganglbauer, Die Kafer 

 von Mitteleuropa, I, p. 422. 1901. Haliplidae, Sharp, Cambridge Natural 

 History, VI, p. 209. 



The Haliplidse are a family of small, aquatic beetles placed by 

 systematists close to the Dytiscidae and probably representing a transi- 

 tion group between the Carabidse and the former family. This group 

 was first recognized as a separate family by C. G. Thomson (Skand. 

 Col., I, 1859, p. 11). Since then the family has been variously re- 

 garded. Some workers have placed it as a tribe, others as a sub- 

 family of the Dytiscidae. 



The family contains only three genera, the genus Haliplus being 

 world wide in its distribution. The total number of known species is 

 about one hundred and twenty-five. The genus Haliplus is repre- 

 sented in Xorth America by about fifteen species, Peltodytes by nine, 

 and Brychius by one. This does not in any way indicate the total 

 number of species, for the beetles are small, not usually observed by 

 collectors, and the family has been sadly neglected by systematists. 



The Haliplidae may be separated from the closely allied families by 

 the following characters : 



Antennnse lo-jointed, inserted on the front between the eyes, under 

 a small ridge; filiform, almost smooth, scattered setae being present 

 (Figs. I and 2) ; clypeus extending laterally to the points of insertion 

 of the antennae, the suture separating it from the front not being 

 very distinct, especially at the sides; gula well defined, broad behind, 

 gradually narrowing at first and then suddenly broadly expanding in 

 front (Fig. 11, ^) ; eyes entire, not emarginate. 



The prosternum is prolonged anteriorly, forming a prominent 

 ridge, steeply declivous in front, into which the head fits closely 

 (Fig. 12). 



Metasternum with a well marked ante-coxal piece, the suture ex- 



