CLASS VIII. ORDERS II. III. & IV. 99 



the number of segments of the body on each side ; 

 feelers two, setaceous. 



ORDER 2. THYSANOURA. 



Having but six feet, with some other organs of 

 movement, which appear like fringes ; no wings. 



LEPISMA, (lepisma,) legs six, formed for run- 

 ning ; mouth with two setaceous and two headed 

 feelers ; body imbricate with minute scales ; tail 

 furnished with extended bristles. 



PODURA, (spring-tail,) legs six, formed for run- 

 ning ; eyes two, composed of eight; tail forked, 

 formed for leaping, inflected ; antennae setaceous; 

 elongated. 



ORDERS. PARASITA. 



Having six feet, no fringe-like organs ; no 

 wings ; crawl upon other animals. 



PEDICULUS, (louse,) legs six, formed for walk- 

 ing ; mouth furnished with an exsert piercer ; an- 

 tennae the length of the thorax ; abdomen depress- 

 ed, sublobate. 



ORDER 4. SUCTORIA. 



5V0 wings ; beak a sucker enclosed in a cylin- 

 dric sheath of two articulated pieces. 



PULEX, (flea,) legs six, formed for leaping ; 

 eyes two ; antennae filiform ; mouth furnished 

 with an inflated, setaceous snout, concealing a pier- 

 cer, abdomen compressed. 



