370 POMONA COLLEGE JOURNAL OF ENTOMOLOGY 



more properly belonging to the dorsal side as would be natural in some in- 

 dividuals that have been studied, giving the formula 1, 4, 3, 1 — 1, 4, 3, 2 instead 

 of 1, 3. 2, 1. The species in some features is variable and shows a tendency 

 to dimorphism. 



While B. xanti, as above indicated, prevails in Southern California and 

 along the coast and in the Coast Mt., the present species replaces it in the 

 Sierras and ranges northward into Oregon and Washington, where it is 

 abundant. 



Genus Litlwbius Leach. 



Two subgenera of this large genus, when considered in the prevalent 

 manner, are known to occur in California. The following key will aid in 

 the sparation of these subgenera and of the species known under each. 



KEY TO .SUBGBNER.\ AND .SPECIES OF Litliobius. 



a. Angles of the 9th, 11th, and 13th dorsal plates produced (Subgenus 

 Lithobius sens str). 

 b. Prosternal teeth 2 — 2 ; coxal pores circular. 



c. None of the last pairs of coxae armed laterally. Spines of anal 

 legs 1 — 3 — 2 — 1, length 1^1 — IS mm. L. angelits Chamberl. 

 cc. Last four pairs of coxje armed both laterally and dorsally. 

 Spines of anal legs 1 — 3 — 3 — 2,; length up to 24 mm. 



L. paucidens Wood. 

 bb. Prosternal teeth 4 — 4 or more ; coxal pores transverse. 



c. Articles of antenn?e 28 — 31 ; ocelli on each side about 30. 



L. aztecus H. S. 

 cc. Articles of antennje 40 or more; ocelli on each side 16 — 21. 



L. chumasanus Chamberl. 

 aa. Angles of none of the dorsal plates produced (Subgenus Metalithobius 

 nom. nov.) 

 b. Prosternal teeth 5 — 5 ; last coxae ventrally armed. Coxal pores 

 2 — 3 — 3 — 2; spines of the first legs 1, 1, 1 ; length 12 mm. 



L. pusio Stuxberg. 

 bb. Prosternal teeth 2 — 2 ; none of the coxae ventrally armed. 



c. None of the posterior coxae armed either laterally or dorsally. 



d. Spines of anal legs 1, 2, 1, 0; coxal pores 1, 2, 2, 2; length 



11 mm. L. paradoxus Stuxberg. 



dd. Spines of anal legs 1, 3, 2, 0; coxal pores 3, 4, 4, 3 ; length 



8 mm. L. remex Chamberl. 



cc. Some of the posterior coxae armed at least dorsally. 



d. Length of body 15 mm.; width of body 2.5 mm.; 3rd and 

 4th joints of anal legs in male deeply furrowed above, the 

 third with a rounded carina at distal end. 



L. carinipes Daday. 

 dd. Length of body 13 mm. or less: width well under 2 mm.; 

 anal legs of male not modified as described under d. 



