106 MODERN CLASSIFICATION OF INSECTS. 



in the structure of their antennae, trophi, and legs, especially merit 

 attention. The body of these insects is generally ovate or elliptic, 

 and more or less depressed ; {Jig. 6.9. Gyrinus (Orectocheilus) villosus, 

 Jig.Q.lO — 17. details of the same insect), the head (Jig. 6. lo.}, 

 is of a moderate size, and somewhat triangular, deeply immersed 

 in the cavity of the prothorax, and furnished with two pairs of eyes, 

 one of which is placed on each side on the upper, and the other on 

 the lower, surface of the head. The antennae (Jig. 6. 14.) are inserted 

 in a cavity in front of the eyes, and are very short; the basal joint is 

 minute, the second large, globular, and produced externally into a 

 long earlike process, with the margins ciliated; the remaining joints, 

 apparently eight or nine in number, being very short and closely 

 united together, forming a fusiform mass. The upper lip (Jig. 6. lo.) 

 is large, horny, and ciliated; the mandibles (j^^. 6. il.) are short, 

 horny, and strongly notched ; the maxillae (Jig. 6. 12.) are flat, horny, 

 curved, acute at the tip, and ciliated internallyj with a prominent 

 lobe below the centre; in the restricted genus Gyrinus (G. natator) 

 the maxilla} are also provided with a slender exarticulate lobe, but in 

 the large exotic species, as well as in (G.) Orectocheilus villosus^ this 

 lobe is entirely wanting ; the maxillary palpi are very short, and 

 4-jointed, the three basal joints being minute, and the third large and 

 ovate. The mentum {^g. 6. 13.) is large, horny, and bilobed, the 

 labium occupying the space between the two lobes ; the labial 

 palpi are short and 3-jointed ; the thorax is short, transverse, rather 

 wider behind, and closely applied to the base of the elytra, which are 

 rather broader than the former; the scutellum is very minute, and 

 occasionally indistinct. The terminal segment of the abdomen ex- 

 tends beyond the elytra, and is furnished with two small cylindrical 

 lobes, which the insect has the power of retracting at will. The 

 fore legs (Jig. 6. 15.) are long and of the ordinary form, except that 

 they are more elbowed, which gives them the appearance of arms 

 enabling them to seize' their prey ; the four posterior legs {Jig. 6.16.) 

 which are used as oars, are, however, very short, rarely extending 

 beyond the side of the body, quite flat and considerably dilated, the 



Ahrens. ■ Neue Schrift. Naturf. Gesellsch. zii Halle, vol, ii Ditto, Fauna, fasc. ii. 



Say, in Trans. Amer. Pliil. Soc. vols. ii. and iv. 



And the general works of Stephens, GyUenhal Fabricius, Olivier, Peril/, Germar (Ins. 

 Sp. Nov.), MacLeay (Annul. Javan.), Chevrolat. 



