CHILOPODA 



475 



young born with the full number of legs: active animals found chiefly in 

 the warmer parts of the earth, where certain species attain great size and 

 are dangerous to man, although it seems doubtful if the bite of any of 

 them is fatal; 5 American genera and about 20 species. The largest 

 known centiped is Scolopendra gigantea L., which attains a length of 27 

 cm. or more, and is found in the East Indies. 



Key to the genera of Scolopendridae here described: 

 aj Pairs of legs 21. 



&! Eyes present 1. SCOLOPENDRA 



6 2 Eyes absent. 



<?! Anal legs not thick 2. CBYPTOPS 



c a Anal legs very thick and short 3. THEATOPS 



a a Pairs of legs 23 4. SCOLOPOCBYPTOPS 



1. SCOLOPENDRA L. Number of pairs of 

 legs 21 ; 9 pairs of slit-like spiracles ; 4 ocelli on 

 each side ; dorsal plate of head heart-shaped and 

 extending back over the first segmental plate: 

 over 50 species, about 10 American, which are 

 found principally in the south. 



S. morsitans L. Body 65 mm. and more 

 long and greenish in color; antennae green; 

 lateral edges dark green; legs short, not longer 

 than the 3 terminal body segments: cosmopoli- 

 tan; rather southerly in America. 



S. heros Girard (S. castaniceps Wood) (Pig. 

 735). Body 10 cm. long or more, yellow and 

 green in color ; antennae 25-jointed ; penultimate 

 joints of legs armed with spines; first dorsal 

 plate with a transverse suture; anal legs long, 

 with 17 to 25 spines: Mexico and the southern 

 states, extending north to Kentucky. 



2. CRYPTOPS Leach. Number of pairs of 

 legs 21; 9 pairs of slit-like spiracles; antennae 

 17-jointed ; eyes absent ; anal legs not thickened : 

 over 20 species, 1 or 2 being American. 



C. hyalina Say. Body about 15 mm. long, 

 smooth and very flat, with reddish-brown head 

 and 2 black internal longitudinal lines: eastern 

 and central states, north to New Jersey and 

 Indiana, often common. 



3. THEATOPS Newport. Similar to Cryptops but with the anal legs 

 very thick and short and with the last dorsal plate twice as large as the 

 preceding: 2 American species. 



Fig. 735 Scolopen- 

 dra heros (Wood). 



