[Plate XVI.] 



[Pioc. B.N.F.C, 1910-1911.] 



Fig. I. 



II. 



Fig. I. Basalt from Spanish Bay, Giant's Causeway— typical 

 section ; x 27. 



Fig. II. -Junction of Basalt (Spanish Bay) with Opal (Onyx), 

 shewing layer of Hullite between the rock and mineral; x 27. 



