In the summer of 1915 I had occasion to visit some of the oilfields of the Western Caucasus, with the view of locating new oil-wells. During my study of the geology of the petroliferous areas on the northern slope of the Caucasus I was able to ride to the Shugo crater, the easternmost of the mud-volcanoes of the Taman peninsula. This crater is situated on the watershed between the Shugo and Chekups Rivers, about five miles south-west of the village Varen-nikovsk. From a distance, as I rode uphill from the wide, alluvial plain of the Kuban River, the picturesque and well-wooded foothills did not disclose any semblance of a mud-volcano, but on climbing the southern slope of the hill, a most unsuspected and striking view was suddenly revealed. Here at my feet lay a nearly perfect crater, about ¾ mile in diameter (Pl. XXI, Fig. 1).