404 



[Proc. BN.F.C, 



is a residual volcanic glass, because not only does it contain 

 inclusions of felspar and magnetite (as in the Carnmoney rock), 

 but also in this case, of grains of augite. The coating or layer of 

 this residual glass around the onyx is quite evident in a section 

 shewing the junction between the onyx and its matrix, and a 

 peculiar feature is the accumulation of the residual glass on the 

 floor of the onyx cavities, as if it had collected in a little pool 

 in the bottom of the latter, while in a molten state. 



When we come to consider the probable origin of the onyx 

 and other minerals in these cavities, the facts lend themselves in a 

 beautiful fashion to illustrate and strengthen the theory developed 

 by the writer and illustrated by him in so many txamples of local 

 mineral deposits in the gas-cavities of lavas, viz., that such 

 minerals are deposited in a regular fashion from a residual magma 

 during the cooling and consolidation of the lava. In the case of 

 the onyx of Spanish Bay, the residual glass with its inclusions 

 of augite, felspar, and magnetite, the coating of the residual glass 

 around the onyx, the thin coating of chlorophaeite, the occasional 

 deposits of calcite following upon the outer coating, and finally 

 the deposition of the opal with inclusions of calcite, present to 

 the student of geogenesis a complete sequence of formation 

 demonstrating clearly the truth of the above hypothesis. 



EXHIBITION OF PLANTS COLLECTED DURING THE SUMMER SESSION, 

 WITH REMARKS ON THEIR HABITATS. 



On Saturday, 17th December, the Botanical Section met in 

 the Museum and enjoyed an interesting informal discussion based 

 on exhibits of plants collected during the Summer Session by 

 various workers of the Section. Rev. C. H. Waddell, M.A., 

 occupied the chair. 



Mr. N. Carrothers and Rev. C. H. Waddell exhibited 

 numerous interesting specimens collected during the preceding 



