542 CLASS VIII. 
First joint of tarsi very short, strictly connate with second, last 
elongate. Antenne with seven to nine joints. Body oblong. Thorax 
narrowed towards the base. 
Sub-genera: Hydrena Kue., Ochthebius Leacu, Hydrochus 
Germar, Helophorus Iuuic. 
Sp. Heloph. grandis Inu1e., Eloph. aquaticus Fasr., DuMERIL Cons. gén. s. 1. 
Ins. Pl. 6, fig. 8, Sturm Deutschl. Faun., Ins. X. Tab. 219, fig. a &e. 
Spercheus Fasr. Maxilla with external lacinia horny, palpi- 
form, acuminate, incurved, ciliated internally, with internal lacinia 
coriaceous, pilose at the apex. first joint of tarsi not less than 
second, last elongate, equalling the first four in length. Antenne 
short, thick, sex-articulate. 
Sp. Spercheus emarginatus Fasr., Panzer Deutschl. Ins. Heft 91, Tab. 4, 
Srurm 1. 1. rx. Tab. 214, Cuv. R. Ani. éd. ill., Ins. Pl. 38, fig. 4; 3°” 
long, dull brown, very convex on the back ; head-shield excised in front : 
this little beetle creeps upon the roots of water-plants. 
This genus forms the transition to the following family, and from the form 
of the under-jaws belongs to the neighbourhood of Gyrinus. 
Family LXIL. Hydrocantharina or Dytiscina. Maxille horny, 
with external lacinia palpiform, articulate. Mandibles, as to the 
greatest part, covered. Four posterior feet natatory, two posterior 
remote from the rest. Body oval, thorax broad, transverse. 
A. Abdomen composed of sia segments. 
Gyrinus Georrr., L. Antenne shorter than head, fusiform, 
with nine joints, auriculate at the base. Eyes divided by the 
lateral margin of head into two parts quite separate. Anterior 
feet long, porrect ; four posterior feet short, broad. Elytra poste- 
riorly rotundate, not covering the apex of abdomen. 
Sub-genera: Orectochilus Escuscu., Cybister Escuscu. (Gyretes 
Brus), Dineutes Mac L. (Cyclous Escuscu., D¥s.), Gyrinus, Hn- 
hydrus Lavorts. Comp. Aupourn et Brunt Hist. nat. des Ins. v. 
pp. 234—242. 
Sp. Gyrinus natator L., Rasen Ins, 1. Tab. xxx1., Panzer Deutschl. Ins. 
Heft 3, Tab. 5, AHRENS et GermMAR Faun. Ins. Europ. 1. Tab. 5; the 
male 2"”, the female 3’” long, blue-black, shining ; the shields are stippled 
in longitudinal rows. These whirling beetles make their appearance early in 
spring in fresh water, revolving in circles on the surface of the water with 
much rapidity. On the least alarm they dive suddenly below. Several other 
European species are figured in AHRENS and GrRMAR Faun. Ins. Hur. 
Tab. II. 
