1901 - 2 .] J. G. Goodchild on Scottish Mineralogy. 
339 
universal occurrence. They remind one of the polysynthetic 
twinning seen on Albite, and, as a matter of fact, there is nothing 
to show that they are not really twin laminae. This remark 
applies to the so-called parallel growths in orthorhombic crystals 
in general. In addition to this feature of somewhat doubtful 
nature there is present in nearly all Cerussites a more or less 
evident tendency to form stellate aggregates by the twinning of 
three (? of six) individuals on m {110} as a twinning plane. The 
angles between any two adjacent brachydiagonal axes does not 
