390 BOTANICAL GAZETTE [NOVEMBER 
Fic. 3.—Tufa cones and xerophytic lava fields, Oahu; open crater to right, Koko 
Crater; hill beyond to left, Koko Head. 
Fic. 4.—Arid headland, Maka-pu’u, Oahu, illustrating ancient lava sheets 
exposed by extensive erosion; note stratification of lava flows and erosion of flows at 
sea level. 
