THE CANADIAN ENTOMOLOGIST. 99 



Probably vviil be found within Wisconsin, where, however, the excessive 

 abundance of L. forficatus doubtless militates against it. 



Genus Lit hob ins Leach. 



Key to Species. 

 a. Posterior angles of the yth, 9th, nth and 13th dorsal plates 

 produced. (Neolithobius.) 

 b. Claw of the anal legs not armed at base, 

 c. Claw of the penult legs unarmed, 



Articles of antennae 30-40 ; prosternal teeth 5 + 5 to 



7 + 7 ; spines of first legs 2, 2, 1-3, 3,2; of penult 

 legs I, 3, 3, 2 L. inordax Koch. 



cc. Claw of the penult legs armed with one spine. 



Articles of antennae 31-36; prosternal teeth, 6 + 6 to 



8 + 8 ; spines of first legs i, 2, i to 2, 2, i ; of penult 

 legs I, 3, 3. i-r, 3. 3, 2 .... Z. tyrannus BoUman. 



bb. Claw of the anal legs armed with one spine. 



c. Claw of penult legs armed with one spine. 



Articles of antennae 31-32 ; prosternal teeth 2 + 2 ; spines 

 of first legs I, I, I ; of the penult, 



1,3,3, I ^- j^'u^fi^^^s Bollman. 



aa. Posterior angles of the 9th, nth and 13th dorsal plates produced. 

 (Lithobius s. str.) 

 b. Claw of anal legs unarmed. 



c. Claw of penult legs unarmed. 



Prosternal teeth 3-3 ; articles of antennae 20-21 ; spines 

 of penult legs i, ^y, i, 2 \ of anal i, 3, 2, o ; claw of 

 female gonopods entire. . . . L. sexdefitatus Kenyon. 



cc. Claw of penult legs armed with one spine. 



d. Articles of antennae 20, or near that number. 



Prosternal teeth 3 + 3 ; spines of first legs 2, 3, 2 ; 



of anal, r, 3, 3, i L. howei Bollman. 



dd. Articles of antennae 30 or above. 



e. Coxal pores transverse j spines of first legs 

 2, 3, 2 L. forficatus Linn. 



ee. Coxal pores round; spines of first legs 



I, 2, 1-2, 2, I L. celer Bollman. 



