PHYLUM ARTHROPODA 



3 11 



crctory organs two malpighian tubules (6). The trachea are 

 branched, and open by a pair of stigmata in almost every seg- 

 ment. The reproductive organs (10) are connected with several 

 accessory glands (8). Eggs are usually 

 laid. Those of Lithobius are laid singly 

 and covered with earth. 



The centipedes are swift-moving crea- 

 tures. Many of them live under the bark 

 of logs, or under stones. The genera 

 Lithobius, Geophilus, and Scutigera are 

 common. The poisonous centipedes of 

 tropical countries belong to the genus 

 Scolopendra. They may reach a foot in 

 length, and their bite is painful and even 

 dangerous to man. 



Order 4. Symphyla. - - The SYMPHYLA 

 are small myriopods 

 with twelve pairs of 

 legs. The head bears 

 antennae, mandibles, 

 maxillulae, maxillae, 

 and a labium. Only 

 two genera, Scolcpen- 

 drella and Scutigerella 

 (Fig. 23 5), and twenty- 

 four species belong to 

 the order. They re- 

 semble certain wing- 

 less insects (APTERA, 



. . . FIG. 235- 



V Ig. 2 59) in habits and SYMPHYLA. 



- Order 

 5 ciiti- 



appearance, but have gerella i^macidatd. 



(From Sedgwick's 



a greater number of Zoology, after Latzel.) 



legs. They live in 



moist places and avoid the light. Their food probably consists 



of small insects. 



FIG. 234. A centi- 

 pede, Lithobius forficatus, 

 dissected to show internal 

 organs. /, antenna; 

 2, poison claw; 3, salivary 

 gland; 4, walking legs; 



5, ventral nerve-cord ; 



6, malpighian tubule ; 



7, seminal vesicle; 8, small 

 accessory gland; Q, large 

 accessory gland; 10, tes- 

 tis; //, alimentary canal. 

 (From Shipley and Mac- 

 Bride, after Vogt and 

 Yung.) 



