520 Div. 3. ARTICULATA.— INSECTA. Class 3. 



First,— Those with very short 10 or 11-jointed antenna', the third and following joints forminij a subcyhndncal, 

 serrated mass. 



Potamophilus, Germ. {Hi/dera, Latr.l, have th.e antenna not lod?:ed in cavities, and rather longer than the head, 

 with the first joint nearly as long as all the rest, and the second short and globular ; the palpi are exserted and the 

 Ciouth is naked. Parnus acuminaiiis, Fabr. 



Diyops, Oliv., has the antenna; shorter than the head, and received in a cavity beneath the eyes, neariy covered by 

 the second joint, which is large, dilated, and ear-like ; the palpi are not exserted. Leach applies this generic name to 

 Dn/ops Dumeiilii, which diftors from the others (which he names Pay-niis) in the length of the feet and form of the 

 thorax, &c. 



Second, — Those with filiform 11-jointed antenns, at least as long as the head and thorax. 



FJmis, Lat. {Limniiis, III.), [insects of very small size], found in water, understones, or the leaves of the water-lily. 



Third,— Those with very short 9 or fi-jointed antenna?, terminated in a nearly solid, oval, or globular mass. 



Macronychus, Mull., has five distinct joints in the tarsi, the body oblong and antenna; 6-jointed. M. i-tuhcrcu- 

 latiis. Mull. 



Georissiis, Latr., has only four distinct joints in the tarsi, the body short and nearly globular, and the antenna; 

 D-jointed. Pimelia pi/ffmwa, Fab., [a very minute shining black insect, with deep rows of dots on the elytra j 

 lather rare]. 



THE FIFTH FA^MILY OF THE COLEOPTERA PENTAMERA,— 



The Palpicornes, — 



Possesses, like the last, antennae terminated in a clul), Avliich is ordinarily perfoliated, but of not more 

 than nine joints in any species, inserted beneath the lateral and advanced margins of the head ; never 

 longer than it and the maxillary palpi, and often shorter than the last-named organs ; the mentum is 

 large and shield-shaped. The body is generally ovoid, or hemispherical and convex. The feet are in 

 the majority proper for swimming, and have only four or five distinct joints, the basal joint being 

 much shorter than the following ; all the joints are entire. 



Those species which have the feet fitted for swimming, with the basal joint of the tarsi much 

 shorter than the following, and the maxillae entirely corneous, compose a first tribe, Ilydrophili, which 

 embraces the genus 



HyDROPuiLus, GeofFroy, — 

 Which Linnaeus regarded only as a first division of his genus Dytiscus, but the anatomy of the two 

 groups differs materially : the digestive canal of the Hydrophili, in its great length and texture, having 

 much analogy with that of the Lamellicornes, approaching the carnivorous tribes only in its 

 biliary vessels. 



Some of these have the body either oval, oblong, and depressed, or long and narrow, with the thorax rough and 

 narrowed behind ; the legs slender ; the tarsi filiform, but slightly ciliated ; the antenna; (always O-jointed) termi- 

 nating in an obconical and nearly solid club. These Palpicornes are all very small; they swim but little and 

 badly, inh.ibiting stagnant water, which they occasionally q>iit in order to hide themselves in the earth or under 

 stones. Tliey compose the family Ilelop/ioridea of Leach, corresponding with the Fabrician genus Elophorus, 



Elophonis, Fab., having the body oval, thorax transverse, and eyes slightly elevated ; and 



Ilydrochns, Germ., having the body long and narrow, the thorax oblong, and the eyes prominent (//. elongatus, 

 Fabr.), have the maxillary palpi terminated by an oval joint ; whilst in 



0(-////(fi/M.s, Leach, the maxillary palpi are terminated by a more slender, short, and conical joint, and the 

 thorax is nearly semiorbicular. E. pyijmtjcus, Fabr. ; Ilydiucna riparia, Latr. 



Ilydrwna, Kng., has the maxillary palpi much longer than the head and antenna', with the terminal joint larger 

 than the preceding, fusiform, and pointed at the tip. They have the aspect of Ochthcbius. E. minimus. Fab. ; 

 Jlydricna riparia, Kugel. 



The other Ilydrophiliens have the body ovoid or subhcniisphorical, and generally convex, with the thorax much 

 broader than long, the tibia' and tarsi generally with long hairs. They compose tlie famWy Ilydrophilidca of 

 Leach, or the genus llydrnpliiliis, Fabr. 



SpcrehcHs, Fabr., hasonly six joints in the antenna', and the clypcus is notched. »5. emarginatits, Fabr. [a very 

 rare British species]. 



Clobaria, Latr., has the body nearly spherical, laterally compressed, and capable of being rolled into a ball like 

 Agathidium. Its antenna; appear to be only 8-jointed, the fifth being dilated internally into a spine, the terminal 

 joints forming a very elongated, nearly cylindrical club, pointed at the tip; the elytra entirely embrace the abdo- 

 men, the four posterior tibia; having a brush of loTig hairs at the tip. The only species, G. Lcachii, is small and 

 exotic: I believe it to be from South America. 



All the remaining Ilydrophiliens have nine joints in the antenna', witli the club oval or ovoid, and the body not 

 contractile into a ball. 



IJydrophUus, Geo!!'., comprises the largest species in the tribe, with the two intermediate joints of the club of 

 the antenna; obtuse at one end, and elongated, arched, and pointed at the other; the first joint of the club is 



