A Remarkable series of crystallised calcites from Cumberland which have been found during the present year deserve description, both on account of their size and beauty, and also by reason of their peculiar form.

The crystals, although obtained from a small area, exhibit great variety of habit and appearance, and fall naturally into the seven groups which are described below. Of these the most remarkable consists of a series of magnificent heart-shaped twins, somewhat similar to the rare but well-known "butterfly twins" of Eyam, in Derbyshire; they result from the same mode of twinning as the latter, but are far larger and more beautiful than any of the Derbyshire twins, frequently measuring four inches in breadth. There are also crystals which exactly resemble the true butterfly twins of Eyam, and others which arc very similar to the rectangular twinned prisms of Wheal Wrey in Cornwall. A second and very rare twin law is also represented among these specimens, in which the rhombohedron, whose edges are truncated by the cleavage planes, acts as twin-plane.