405 



It is a long jump from the jacobsoni-mandihle to that of esau 

 (text-lig. 19), and \vc must expect that a species will be dis- 

 covered which bridges over this wide gap. The homology of 



Fig. 15. — Mandible of Forfícula aiiriculínin. 



Fig. 16. — Mandible of Hcmimeriis talpoiiics. 



Fig. 17. — Mandible of Arixeuia jacobsoui (left side). 



Fig. 18. — Mandible of Arixeuia jacobsoui (right side). 



Fig. 19. — Mandible of Arixeuia esaii. 



the various portions of the rsi? «-mandible is quite clear. The 

 mandible is reduced in size, being very much smaller as compared 

 with the size of the specimens tliaii in an\- ulher Hermapteron 



