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79 . 
GYRINUS BICOLOR. 
Order Coleoptera. Fam. Gyrinidse Leach. Gyrinites Lat. 
Type of the Genus G. Natator Linn. 
Gyrinus Linn., Fab., Oliv., Lat., Marsh, Gyll., Leach, $c. 
Antennae inserted beneath the superior portion of the eyes, at 
the side of the clypeus, very short, rigid, porrected, 9 -jointed • 
1st joint large globose, produced on the external side in a tri- 
angular compressed, ciliated lobe j the other joints forming a 
clavate, cylindric, arcuate mass arising from the upper side of 
the 1st joint, basal joint pedunculate, 3rd and 6 following trans- 
verse, terminal joint semi-oval (f. 6). 
Labrum rigid, exserted, transverse, convex, rounded before and 
ciliated (1). 
Mandibles scarcely exserted, strong, corneous, very much bent, 
apex dilated transversely, bidentate, with a tooth on the internal 
edge towards the base (2) . 
Maxillae acute, ciliated with rigid bristles, a palpiform, exarti- 
culate bent lobe, on the internal side, being a modification of 
the internal palpus of the Dyticidae. Palpi incrassated, 4 -jointed, 
1st joint small, 2nd and 3rd somewhat cup-shaped, 4th large 
ovate (3). 
Menlum large, corneous, somewhat oval, bilobed, sides semi- 
orbicular. Palpi small, 3-jointed, 1st joint minute, 2nd clavate, 
3rd robust, conical. Lip corneous, small, quadrate, shorter than 
the mentum (4). 
Head large , somewhat trigonate. Eyes 4, circular, 2 above and 2 be- 
neath the antennae. Thorax short, transverse , sinuated before and 
behind. Elytra with the margins acute. Scutellum minute. Wings 2. 
Pectus and Abdomen carinated in the middle. Anterior feet 
formed for walking, elongate, geniculate , porrect ; four posterior 
short, compressed, membranaceous , formed for swimming, external 
edges fimbriated with compressed hairs. Thighs and Tibiae short, 
trigonate in the 4 posterior legs, the hinder having 2 little spurs at 
the internal angle. Tarsi 5 -jointed, the terminal joint being the 
longest in the anterior pair, compressed and produced internally in 
the 4 posterior pair, the terminal joint being very minute. Claws 2, 
long in the forefeet, minute in the others (5 a fore leg, 5* a hind 
leg). 
Bicolor Fab. Ent. Syst. v. 1. pars 1. 202. 2. Gyll. 1. 142. 2. 
Elongatus Marsh 100. 4. 
Long, narrow, caeruleous-black, shining. Thorax with a trans- 
verse impression before the middle. Elytra very long, appear- 
ing attenuated posteriorly, truncated, rounded, having 1 1 finely 
punctured striae on each, inflected margin ferruginous. Suture 
aeneous. Abdomen villose above, black beneath, ferruginous at 
the apex. Mouth and centre of pectus ferruginous. Legs 
ochraceous. Male much narrower than the female. 
In the Author's and other Cabinets. 
