Wa 
544 CLASS VIII. 
B. All the tarsi with five joints. First three joints of anterior tarsi in 
males broad, transverse. 
Colymbetes Cuatrv. Scutellum conspicuous. (Sub-genera : Colym- 
betes, Hybius Ericus., Agabus Leacu, Ericus.) 
Sp. Dyt. fuscus L., Panzer Deutschl. Ins. Heft 86, Tab. 5, CLAIRVILLE 
Entom. helvet. 1. Pl. 29, fig. B, &e. 
Laccophilus Luacu. Scutellum covered. Antenne thin, seta- 
ceous. 
Sp. Dyt. hyalinus DE Grrr, Laccophilus minutus Sturm, Dyt. obscurus, 
PanzeER Deutschl. Ins. Heft 26, Tab. 3, &e. 
Noterus Cuatrv. Scutellum covered. Antenne incrassated in the 
middle (especially in males). 
Sp. Dyt. crassicornis FaBr., &c. 
C. Anterior tarsi in both sexes subequal. (First and second pairs of 
feet with tarsi of four joints, the penultimate joint obsolete or concealed.) 
Hyphydrus (1u11c., GYLLENH. Sp. of Hydrachna Fasr.), Hydro- 
porus CLAIRY. 
Sp. Dytisc. palustris L., Dyt. lituratus PANZER Deutschl. Ins. Heft 14, Tab. 4; 
—Dyt. rufifrons DuFtscHM., Sturm 1. 1, 1x. Tab. 207, fig. a, &c. 
Pelobius Scuornn., Ericus. (Species of Hydrachna Fasr., 
Hygrobia Later.) Antenne filiform, short, with eleven jomts. 
Head sub-exsert, with eyes somewhat prominent. Labrum emar- 
ginate. Thorax very short, much broader than head. Posterior 
coxe narrow. ‘Tarsi all with five joints, slender. Scutellum 
distinct. 
Sp. Pelobius Hermanni, Hydrachna Hermanni Fasr., PANZER Deutschl. Ins. 
Heft tor, Tab. 1, Sturm 1. 1. vii1, Tab. 200. 
Haliplus Larr. Antenne scarcely longer than head, filiform, 
thin, with ten joints. Labrum entire, with margin ciliated. Pos- 
terior coxe narrow, covered by an orbicular plate. All the tarsi 
with five joints. (External maxillary palps with last joint narrow, 
subulate). 
Sp. Haliplus ruficollis, Dyt. ruficollis, Dk GEER Jns. Iv. Tab. 16, fig. 9, 
PanzeR Deutschl. Ins. Heft 14, fig. 10. 
Cnemidotus Iuuic., ERICHS. 
Note.—Differs from Haliplus in the last joint of external maxillary palps 
being greater, conical. Sp. Haliplus cesus GYLLENH., PanzER Deutschl. 
Ins. Heft 14, Tab. 7, Df&snan et AuBH, Jconogr. Vv. Pl. 3, fig. 2. 
