No. 437] VARIATION IN UTHOBIUS FORFICATUS. 



TABLE i. 



These data are represented graphically i 



lootemales , 19-96 ±-'5 2.245^.107 11.25 



100 mixed , 21.41 ±.15 2.35 ±.u .0.99 



For the 100 mixed individuals, 49 females and 5 1 males, counts 

 were made of : 



r. The number of prosternal teeth. 



2. The number of joints in the antennas. 



3. The number of coxa! glands, pits or pores which are 

 found on the coxa; of the last four pairs of legs (the 12th, 13th, 

 14th, and 15th). These data are given in their entirety in 

 Appendix A. 



According to the key for the different species of Lithobius in 

 Bollman's "Myriapods of North America" the number and 

 arrangement of the coxal pores, the spines on the legs, the 

 number of joints of the antennae and the prolongations of the 

 posterior angles of certain of the dorsal plates are the decisive 

 specific characters. I append an abbreviated key taken from 

 Bollman ('87) for the two species L. forficatus and L. mulH- 

 dentatus. I intended to include in the data counts of the ocelli 

 also but it was impossible. As Bollman says "the ocelli are 

 distinct or not" and in many cases the fusion was nearly as 

 complete as in Seutigera where there is a close approach to the 

 facetted compound eye. 



