I am indebted to the kindness of my friend Mr J. Y. Buchanan, M.A., the chemist and physicist to the “Challenger” expedition for the specimen which forms the subject of this note.

In speaking of the geology of Kerguelen Island, Mr Buchanan thus describes the occurrence of this zeolite (vide Proc. Roy. Soc., vol. xxiv. p. 617).

“The horizontal beds which form the mass of the land are basaltic, and vary from 10 to 20 feet in thickness, being generally compact; but, in ascending the hill, beds are met with frequently, which contain large amygdaloidal cavities filled with zeolites, principally analcite and heulandite (stilbite). These minerals are very plentiful in this part of the island, and when rounded by the action of the water they form remarkable white pebbles on the otherwise darkcoloured volcanic sand. Up to the summit the alternation of beds of compact sub-columnar rock of amygdaloid is pretty regular.