"An unusual appinitic sill intrudes and thermally alters regionally metamorphosed Dalradian sediments near Killin, Perthshire. The sill is composed of ultrabasic, basic, dioritic, and acid varieties, the last two being present only in minor quantity. The dioritic intrudes, and is chilled against the ultrabasic type. The appinitic varieties and contact Dalradian rocks are described together with their field relationships." Chemical analyses are included.