“It is a continuation of one of the mine tunnels, passing entirely through the mountain to the valley beyond. The mines have been worked by the ancestors of this race for an almost incalculable length of time. The mountains are honeycombed with their shafts and tunnels. Back of the gold-bearing quartz lies an enormous deposit of altered peridotite, which contains diamonds, in the search for which it evidently became necessary to extend one of the shafts to the opposite side of the mountain, possibly for purposes of ventilation. This tunnel and the trail leading down into Opar are the only means of ingress to the valley. From time immemorial they have kept the tunnel guarded, more particularly, I imagine, to prevent the escape of slaves than to thwart the inroads of an enemy, since they believe that there is no fear of the latter emergency. The trail to Opar they do not guard, because they no longer fear the Oparians, and know quite well that none of their Gomangani slaves would dare enter the valley of the sunworshipers. For the same reason, then, that the slaves cannot escape, we, too, must remain prisoners here forever.” “How is the tunnel guarded?” asked Tarzan. “Two Bolgani and a dozen or more Gomangani warriors are always upon duty there,” replied the old man. “The Gomangani would like to escape?” “They have tried it many times in the past, I am told,” replied the old man, “though never since I have lived here, and always they were caught and tortured. And all their race was punished and worked the harder because of these attempts upon the part of a few.” “They are numerous—the Gomangani?” “There are probably five thousand of them in the valley,” replied the old man. “And how many Bolgani?” the ape-man asked. “Between ten and eleven hundred.” “Five to one,” murmured Tarzan, “and yet they are afraid to attempt to escape.” “But you must remember,” said the old man, “that the Bolgani are the dominant and intelligent race—the others are intellectually little above the beasts of the forest.” “Yet they are men,” Tarzan reminded him.