CAP AND BUTTON ISLES, two small islands in the Straits of Sunda, which are supposed to be of volcanic origin. They are round in their figure, and their sides are steep and have a naked appearance. One of them, the Cap, is penetrated by two large caverns running horizontally into the rock, which are famous for producing the edible bird-nests so highly prized by the Chinese, and which constitute a great article of traffic. Long. 105. 48. E. Lat. 5. 49. S.