ENTOMOLOGY. 



673 



Tribe III. Dyticides. 



This tribe is at once distinguished from the Carabici, 

 by the superior length of the hinder legs, which are 

 formed for swimming. 



I. Labial and external maxillary palpi filiform. 



A. All the tarsi with five joints, the last of which is 

 longest. 



Genus XLVII. Dyticus. Geoff. Illig. Latr. 



Dytiscus. Linn. Fabr. Oliv. Lam. 



Scutellum distinct ; anterior tarsi of the male patelli- 

 form ; elytra of the female sulcated ; external maxillary 

 palpi with the last two joints equal. 



Sfi. 1. Marginalis. Ovate, olive-black above ; luteous 

 red beneath the scutellum, of the same colour with the 

 elytra ; clypeus, whole margin of the thorax, and border 

 of the elytra, red clay-colour ; bifurcatur of the sternum 

 lanceolate. 



Inhabits Europe. 



Linnaeus considered the sexes of this insect as dis- 

 tinct species, under the names Dytiscus semistriatus and 

 marginalis. 



Dytiscus circumflexus of Fabricius, the Jlavoscutellatus 

 of Latreille, is very abundant near London. It is dis- 

 tinguished from marginalis by its more elongatef shape, 

 by the bifurcate processes of the sternum being spine- 

 shaped, and by the colour of the scutellum, which is in- 

 variably ferruginous. 



Genus XLVIII. Colymbetes. Clairville. 



Dytiscus. Linn. Fabr. Gyll. 



Dyticus. Latreille. 



Scutellum distinct ; anterior tarsi of the male dilated, 

 but not patelliform ; elytra of the female not sulcated ; 

 exterior maxillary palpi with the last joint longer than 

 the one before it. 



Sfi. 1. Bufiustulatus. Oval, depressed, black ; finely 

 striated above the elytra with impressed points, which 

 are obsolete ; antennx labrum, two frontal spots ; an- 

 terior tibiae and tarsi obscure red ; eyes gray. 



Dytiscus bifiustulatus. Linn. Fabr. 



Dyticus bifiustulatus. Latr. 



Dytiscus carbonarius. Gyll. 



Inhabits the European waters every where. 



Genus XLIX. Laccophilus. Leach. 



Dytiscus. ' Linn. Marsh. Gyll. 



Scutellum, none. Antennae, setaceous. Palpi, fili- 

 form. 



Sfi. 1. Minutus. Greenish-testaceous; legs yellowish. 



Dytiscus Minutus. Linn. Marsh. Gyll. 



Laccofihilus Minutus. Leach. 



Inhabits stagnant waters. 



Genus L. Noterus. Clairv. Latr. 



Dytiscus. Fabr. Marsh. 

 Dyticus. Latr. 



Scutellum, none. Antennae, with a fifth or seventh 

 joint dilated. Labial palpi, bifurcate. 



Sfi. 1 . Crassicornis. Oval, convex, brown ; head and 

 thorax ferruginous; elytra sprinkled with impressed 

 dots ; antennae of the male thick. 

 Dytiscus crassicornis. Fabr. Oliv. 

 Dyticus crassicornis. Latr. 



Inhabits Germany and France. Thorax in each sex, 

 with margined sides, with an impressed longitudinal line. 

 B. The four anterior tarsi, with four joints ; no 

 scutellum. 

 Genus LI. Hydroporus. Clairville. 

 Hyphydrus. Illig. Dumeril. 

 Vol VIII. Part II. 



Dytiscus. Marsh. 



Body oval ; the breadth exceeding the height. 



Sfi. 1. Fusculus. Oval, plain, black, pubescent, finely 

 punctulated ; elytra fuscous ; antennae, feet, shoulders, 

 and external margins of the elytra, rufous, 



Dytiscus fusculus. Illiger, Latr. 



Inhabits the waters of Europe. 



Genus LIJ. Hyphydrus. Illig. Clairville. 



Hydrachna, Fabr. 



Dytiscus. Linn. Marsh. 



Body nearly globose ; the height exceeding the 

 breadth. 



Sfi. |. Fcrrug incus. Obscure ferruginous, impunc- 

 tate ; the base of the elytra with an impression at the 

 base of the suture. 



Dytiscus ovatus. Linn, 



Hydrachna gibba. Fabr. 



Hyfihydrus ferrugineus. Latr. 



Inhabits Europe. 



Dytiscus ovalis of Illiger, Hydrachna ovalis of Fabri- 

 cius, differs from the above species, in having a more 

 shining colour, in having the elytra darker and distinctly 

 and widely punctured. May not the above be but sexual 

 distinctions? Such is the opinion of Dr Leach, who 

 could never find the sexes of each kind. 



C; All the tarsi five-jointed ; the first joint largest ; 

 with a scutellum. 



Genus LIII. P^lobius. Schbnher, Leach. 



Hygrobia. Clairville. 



Hyphydrus. Latreille. 



Dytiscus. Marsham. 



Hydrachna. Fabricius. 



Antennae with the first joint longer and thicker than 

 the rest. 



Sfi. 1. Hermanni. Black; head, transverse band on 

 the thorax ; base and border of the elytra and feet 

 ferruginous.. 



Dytiscus Hermanni. Marsh. Oliv. 



Hydrachna Hermanni. Fabricius. 



Hyfihydrus Hermanni. Latr. Gen. Crust, et Ins. 1 . 

 tab. 6. fig. 5. 



Inhabits the marshes of France and England. The 

 last segments of the abdomen, when rubbed against the 

 elytra, produce a noise. 



II. External maxillary and labial palpi subulate ; 

 hinder thighs covered at their base with a shield-shaped 

 plate. 



Genus LIV. Hauplus. Latreille. 



Hoplitus. Clairville. 



Cnemidotus. Illiger. 



Dytiscus. Geoffroy, Marsham. 



Scutellum, none ; body oval, thick. 



Sfi. 1. Jmfiressus. Yellowish or ferruginous ; elytra 

 with some obsolete abbreviated punctured striae, and 

 with blackish lines and spots. 



Inhabits France, England and Germany. 



Tribe IV. Gyrinides. 



Internal maxillary palpi composed of one part. An- 

 tennae very short. Eyes divide so as to appear as four. 

 Four hinder feet compressed, foliaceous, formed for 

 swimming. 



Genus LV. Gyrinus. Linn. Fabr. Latr. Gyll. 



Sfi. l. Mitator. Oval; elytra with punctured strise • 

 the inflexed margin testaceous. 



Gyrinus Mitator. Gyll. 



Inhabits stagnant waters. 



4 Q 



