474 MYMIAPODA 



Key to the families of Chilopoda: 

 Qi Dorsal plates 15 or more. 

 61 Pairs of legs 21 or more. 



Cy Pairs of legs 31 or more ; no eyes 1. Geophilidae 



c. Pairs of legs 21 or 23 2. Scolopendridae 



hj Pairs of legs 15 3. Lithobiidae 



Cj Dorsal plates 8 ; 15 pairs of very long legs 4. Scutigeridae 



Family 1. GEOPHILIDAE. 

 Body very long and slender, with 31 to 173 segments, each composed 

 of 2 unequal subsegments, with an equal number of pairs of legs and 

 ventral plates; number of pairs of spiracles usually 2 less than the pairs 

 of legs ; antennae 14-jointed ; eyes absent ; young born with the full number 

 of legs ; habits relatively sluggish : about 5 American genera and 50 species. 



1. Geophilus Leach. Number of segments 31 to 93; first pair of 

 maxillae with a pair of palp-like projections ; dorsal plates with 2 longi- 

 tudinal grooves: about 20 American species. 



G. rubens Say {G. cephalicus Wood). Body wide, especially the 

 head, about 45 mm. long, with 47 to 53 pairs of legs; color orange 

 anteriorly, dark olive over a greater part of the body, with a broad, 

 double, black median line; last ventral plate wide; anal legs hardly 

 longer than the others: common throughout the eastern and central 

 states. 



G. -umbraticus (McNeill). Pairs of legs 49, with long hairs, the 

 anal legs being slender and but little modified; color light orange in 

 front and behind and fuscous between ; body hairy above ; length 21 mm. : 

 central states, often very common. 



2. LiNOTiENiA Koch. Number of segments 39 to 70; head very 

 small; first pair of maxillae without palp-like projections and with the 

 exterior part 2-jointed; anal legs 6-jointed; claw of prehensile legs with 

 a basal tooth: 13 American species. 



L. fulva (Sager). Body smooth, about 20 mm. long, tapering ante- 

 riorly, and with 47 pairs of legs, yellowish-orange in color; antennae 

 thread-like; basal joint of last pair of legs in male much thickened: 

 central states, often common. 



L. ruber (Bollman). Body about 35 mm. long and 2 mm. wide, 

 with 67 to 73 pairs of legs ; color bright red in life, yellowish in alcohol ; 

 first pair of legs shorter than the second ; last pair not much longer than 

 the first and thickened : central states, often common. 



Family 2. SCOLOPENDRIDAE. 

 Body elongate, with either 21 or 23 segments and an equal number 

 of pairs of legs and ventral plates; number of spiracles 9, 10, or 11; 

 antennae with 17 to 31 joints; eyes, when present, consist of 4 ocelli each; 



