CLASSIFICATION 3 



connected by transverse commissures. Integument delicate. Some 

 fifty species are known. Example, Peripatus (Fig. 3). 



Diplopoda. Terrestrial. Two regions, head and body. Body 

 usually cylindrical, with numerous segments, most of which are double 

 and bear two pairs of short limbs, which are inserted near the median 

 ventral line. Eyes simple, antennae short, usually seven-segmented, 



PIG. 3. Peripatus capensis. Natural size. After MOSELEY. 



mouth parts consisting of a pair of mandibles and a compound plate, 

 or gnathochilarium. Genital openings separate, anterior in position 

 (on the second segment of the body). Example, Spirobolus (Fig. 4). 



Pauropoda. Terrestrial. Two regions, head and body. Body 

 elongate, twelve-segmented, with nine pairs of functional legs; each of 

 the first five apparent terga consists morphologically of two united 

 terga. Eyes absent, but a pair of eye-like spots may be present. 

 Antennae characteristic; with four proxi- 

 mal segments and a pair of distal 

 branches bearing three filaments in all. 

 Mouth parts represented by mandibles, 

 maxillae (?) and labium (?). A single 

 genital opening (female) or a pair of 

 openings (male) on the third body 

 segment. Minute arthropods, at most 

 about one millimeter in" length. Example, 

 Pauropus. 



Chilopoda. Terrestrial. Two regions, 

 head and body. Body long and flat- 

 tened, with numerous segments, each of 

 which bears a pair of long six- or seven- 

 segmented limbs, which are not inserted near the median line. Eyes 

 simple and numerous (agglomerate in Scutigera) antennae long, many- 

 segmented. A pair of mandibles and two pairs of maxillae. A single 

 genital opening, on the preanal segment. Example, Scolopendra (Fig. 5) . 



Symphyla. Terrestrial. Two regions, head and body. Head 

 prognathous, with a Y-shaped epicranial suture. Eyes few. Antennae 

 long, multiarticulate. Four pairs of mouth parts; mandibles two- 



Pic. 4. A diplopod, Spirobolus 

 marginatus. Natural size. 



