Mr. Herbert J. Jessop, who has recently returned from a journey in Eastern Peru, kindly placed in my hands, for examination, some specimens of graptolites which he had obtained on the River Macho, one of the tributaries of the Inambari, near the celebrated mountain Capac Orco, or Monte Bello, in the province of Carabaya, Peru (lat. 13° 40′ S.; long. 70° 10′ W.). The locality is situated on the north-east of the main watershed, and the rivers flow eventually into the Amazon. The difficulties of travelling make it likely that a long time will elapse before other specimens are forthcoming from this locality; it seems desirable, therefore, that some account of these should be published.