280 INSECTS. COLEOPTEUA. 



Gen. HETEROCERUS, Bosc, Fab. 



Tarsi short, with four distinct joints, and folding on the exte- 

 rior side of the legs, which are triangular, spinous, or ciliated ; 

 antennae short, with the last seven joints forming a dentated 

 and arched club ; body oval, depressed, and pubescent. 



H. marginatus, Fab. Body hairy, obscure, with the margin of the 

 elytra and some dots on their surface ferruginous. 1 line long. 

 Found near Paris, in damp places. Lat. Hist. ix. pi. 78, fig. 4. 



Gen. DRYOPS, Oliv. 



Tarsi with five joints, large, increasing towards the end, and 

 terminated by two strong hooks ; antennas shorter than the 

 head, of nine or ten joints, folding into a cavity under the 

 eyes, the last six or seven joints forming a cylindrical and 

 dentated club ; mandibles strong and dentated at the point ; 

 palpi terminated by an oval joint ; body elliptical, with the 

 head sunk in the thorax to the eyes ; pre-sternum dilated. 



This genus has been subdivided by Latreille and Dr Leach into several. Those 

 species with the body thick or convex are the Parnidea of Leach ; those with the 

 antennae free, or not folding into a hollow grove, and without a dilatation at their 

 base, form the genus Potamophilus of Germar, or the Hydera of Latreille ; those 

 with filiform antennae, the la^t joint longest, form the genus Elmis ; and the genus 

 Dryops is restricted to those which possess a groove for the antennae, and the second 

 joint dilated into an auricle. 



D. auriculatus, Lat. (Parnus prolifericorms, Fab.) Blackish or 

 dark olive, dotted, downy and rough with small hairs ; club of 

 the antennae reddish ; an impressed line on each side of the tho- 

 rax ; feet shorter than the body. Inhabits France, on aquatic 

 plants Lat. Gen. ii. 55. 



Gen. MACRONYCHUS, Muller. 



Antennae with six joints, inserted at the internal margin of the 

 eyes, of which the first is the longest, the next four cylindri- 

 cal, and the last forming an oval club ; mandibles corneous 

 and bifid at the point ; palpi short, equal ; feet long and slen- 

 der ; tarsi very long, terminated by two large hooks. 



M. quadrituberculatus, Mull. Bronze black, with the antennae red- 

 dish j the anterior margin of the thorax and the exterior border 

 of the elytra pale or yellowish. Germany Lat. Gen. ii. 58. 



Gen. GEORISSUS, Lat. 



Tarsi long, filiform, with four distinct joints; antennae very short, 

 of nine joints ; the last three forming an orbicular club ; pal- 

 pi short, thickest at their extremity ; body globular, with the 

 head concealed in the thorax. 



G. pygmceus, Lat Nouv. Diet. xiii. 96. 



FAMILY V. PALPICORNES. 

 Antennae short, composed of six or nine joints, inserted in a 



