The Third International Phytogeographic Excursion, which had been proposed in i9i5 by the Swiss botanists, and which had been postponed on account of the World War, was held during the summer of 1923. The main party met in the Botanical Museum of the Technical High School in Zurich and was addressed by the head of the High School, the rector of the University, and the committee of arrangements composed of Drs. C. Schroeter, H. Brockmann-Jerosch and Ed. Ruibel. After the lectures, delivered in French and German, the party inspected the finely appointed laboratory of botany with its important collection of teaching material. The first excursion was taken on July 21st to study the Sihlwald, with midday meal at the Hotel Hirschen Albis, while the afternoon was spent in a visit to Utliberg and Uto-Kulm; July 22nd was spent near Zurich in a visit to the mixed forest of Loorenkopf and Adlisberg, with an inspection of the forest experiment station at Adlisberg under the guidance of the director of the station. A two days' excursion with return to Zurich on the evening of July 24 was taken via Brunnen, Luzern and Alpnachstad to the summit of Mt. Pilatus, where the night was spent, the return down the mountain being made on foot the next day. Zurich, which had been the headquarters during the first five days of the excursion, was finally left on July 25. The party entrained for Chur and in rapid succession until August 13, when the party disbanded at Kleine Scheidegg at the foot of the Jungfrau, the points of principal ecologic and phytogeographic interest were visited in Switzerland and Northern Italy. Only some of the important features of the excursion can be mentioned within the limits of this synopsis. At Chur-Reichenau xerotherm vegetation was studied. The party proceeded by Albula Pass into the Engadin, traveling from Bevers to Zernez in the Lower Engadin. Zernez is the gateway to the Swiss National Park, which was visited, as well as the summit of the Buffalora, which commands a view of the Ortler in Tyrol. The botanists found the flora of Alp Buffalora and Mt. Buffalora, just outside the National Park limits, rich and interesting. The forest vegetation in the Upper Engadin between St. Moritz and Pontresina was found to consist of a mixture of Larix decidua, Picea excelsa, Pinus silvestris var. engadensis and woody undergrowth of Vaccinum11 Myrtillus, V. uliginosum, Rhododendrumsn ferrugineuuw, B etula pubescens, Pyrus aucuparia, etc.,