ARTHROPODA 



IQI 



strong, clawlike organs, called the maxillipeds, and at the tip ol 

 the claws is the opening of a poison gland. With these claws 

 the largest tropical species can inflict wounds which are 

 dangerous even to man. In sonic genera the embryos are 

 essentially like the adult; in others there is a larva and 

 metamorphosis. The centipedes are carnivorous. 



• Order 2. Diplopoda 



The Diplopoda (Gr. &nr\6<; } double, and ttov$, foot) comprise 

 the millipedes (Fig. 188), — sometimes called galleyworms, 

 whose body is nearly cylindrical, and provided with a relatively 

 hard chitinous cuticula. Like the centipedes, they exhibit great 

 variation in size, and in the tropics are found twelve or more 

 centimeters long. The antennae are short, having only seven 

 segments. There are only two pairs of mouth parts, the mandi- 



FlG. 188. lulus terrestris, a "wire worm," enlarged about three and a half diameters, i, 

 antenna; 2, eye; 3, legs; 4, opening of gland. (From Shipley and MacBride's Zoology.) 



bles and the first maxillae. The first four or five trunk segments 

 bear each a single pair of short appendages, attached near the 

 median ventral line. The succeeding segments, with the excep- 

 tion of a few at the posterior end of the body, are really double 

 segments, two being fused into one, so each bears two pairs of 

 appendages. There are thus often over two hundred pairs of 

 legs on one animal. There are no maxillipeds or poison glands, 

 as in the centipedes; the millipedes are entirely harmless, and 

 feed usually on decaying vegetable matter, sometimes on living- 

 plants. When disturbed they often roll up into a ball or spiral, 

 thus protecting the softer ventral side of the body. The em- 

 bryos develop into larvae with only three pairs of legs, which by 

 successive moults metamorphose into the adult. 



