2,7:3,6-Dimethanonaphth[2,3-b]oxirene,3,4,5,6,- 9,9-hexachloro-1a,2,2a,3,6,6a,7,7a-octahydro-,(1aR,2R,2aS,3S,6R,6aR,7S,7aS)-rel-,mixt. with (1R,2R,3&acirc