It does not appear to be at present a matter of fixed precedent whether the Annual Meeting of the Mineralogical Society should or should not be associated with the delivery of a Presidential Address ; and I had hoped, knowing how slightare my claims to the honour which you have conferred upon me, to have escaped until I give place to a worthier successor. But our Honorary Secretary has intimated to me that he would prefer 'a few remarks' and as I feel so strongly the obligations under which he has placed the Society by the free gift of his valuable time, his will is law to me.

The rare occurrence of the primitive rhombohedron r {100} with little or no modification on crystals of calcite has induced me to bring to the notice of the Society some very fine pale lilac crystals exhibiting this unusual habit.

These specimens were raised a few years ago from the Llandeilo flags strata in the Tankerville lead mine, near Shelve, Shropshire.

Occurrence. At the Emerald Mines of the Valley of Muso, New Granada, in a gangue composed of anthracitic calcite and pyrites. Lustre, vitreous to resinous ; colour, yellowish brown to honey-yellow. An acute hexagonal pyramid with striations perpendicular to the axis. The crystal measures 84 millim. in length, and 12 millim. in thickness at the base.

The pyramid is perfect and its apex is intact.

All the specimens of Parisite which have been hitherto received, and are found in European Museums, exhibit a truncated hexagonal pyramid. This section is due to a very easy basal cleavage.

When I submitted my Paper on Enargite (Min. Mag. Vol. vi. p. 49) to this Society, I was unable to give the exact locality of the mineral. As the territory of Montana embraces a considerable extent of land, I was therefore desirous of ascertaining the position of the mines yielding the ore.

Having during the past summer had the opportunity of visiting the locality, I am now able to give some further particulars.

In this Paper the author directs attention to some localities in Scotland where the aetinolite forms of hornblende are to be found.

In Aberdeenshire the actinolite occurs as sheaf-like groups, irregularly distributed through a felspathic base ; also as slender crystals, extending sometimes to the length of eighteen inches, in a dioritic rock. On the hill of Heshgarnich, in Perthshire, this variety of hornblende occurs in nests, also in fan- or sheaf-like bundles of a black colour ; and on the north side of the hill it is found in blade-like forms distributed through a glistening micaceous schist.

During the past few years the study of the minute structure of minerals and rocks has received the attention of so many able geologists, that microscopical mineralogy and petrography may now be regarded as a fairly established means for the identification and diagnosis of inorganic species. As a special instance, I may point to Heddle's researches on Amazonstone, where the discrepancy of its chemical constitution from normal orthoclase, and its aberrant crystalline form, are accounted for under the microscope, with polarised light, by minute structural peculiarities which support the view that it is composed, not of orthoclase and albite, as has been supposed, but of orthoclase and a paragenetic constituent, allied to, if not identical with, oligoclase.