Paper, 'Note on the microscopic structure of rock specimens from three peaks in the Caucasus' by Thomas George Bonney Bonney writes: 'Although our knowledge of the petrology of the Caucasus has been considerably augmented of late years through the labours of Abich, Favre, Tschermak, and others, so much ground still remains un­trodden among its mountain peaks that hardly any specimen can be entirely without interest.' Annotations in pencil and ink. Subject: Geology Received 5 April 1887. Read 5 May 1887. A version of this paper was published in volume 42 of the Proceedings of the Royal Society as 'Note on the microscopic structure of rock specimens from three peaks in the Caucasus'. 1887