This order comprises the well-known carnivorous Centipedes and their allies, and is characterised by the number of legs being rarely indefinitely great (usually from 15 to 20 pairs), by the composition of the antennae out of not less than 14 joints (14 to-40 or more), and by the structure of the masticating organs. These consist of a pair of mandibles with small palpi, a labium, and two pairs of "maxillipedes" or foot-jaws, of which the second is hooked, and is perforated for the discharge of a poisonous fluid. There is not more than one pair of legs to each somite, and the last two limbs are often directed backwards in the axis of the body, so as to form a kind of tail. The body in all the Chilopoda is flattened, and the generative organs open at the posterior end of the body.

Fig. 170.   Centipede (Scolopendrd).

Fig. 170. - Centipede (Scolopendrd).

Scolopendra (fig. 170), Lithobius (fig. 169), and Geophilus are common European genera of this order. The ordinary Centipedes of this country are (unless in exceptional cases) perfectly harmless; but those of tropical regions sometimes attain a length of a foot, or more, and these are capable of inflicting very severe, and even dangerous, bites.