GEOLOGIC RECONNAISSANCE OF MINDANAO AND SULU. 475 Much less has been accomplished in relation to the geology, but there is ample excuse for this lack of results. To use the expression of Dr. G. F. Becker, "such work in a country where the natives are not on the best of terras with you is more exciting than profitable" Among our Spanish predecessors, Sainz de Baranda, Centeno, Montano, Espina, and Abella have contributed to our knowledge of the geology of Mindanao. The work of the latter was confined almost entirely to the Misamis region, but it is the best of all the contributions from that part of the island. The following appear among other Europeans who collected in Mindanao or studied its geology: Semper, Richthofen, Minard, and Renard. K. Martin worked on some fossils which came from Mindanao and Oebbeke described certain rocks collected on that island. Martin and Oebbeke have never been in the region. Dana, Ashburner, and Nichols were Americans who visited Mindanao before the American occupation and who contributed to a knowledge of its geology and finally, Dr. Becker was in the Archipelago in 1898, just at the outbreak of hostilities with the natives. Guillemard and Becker seem to have been the only investigators who touched at any part of the Sulu group. The former barely mentions Cagayan de Sulu, and the latter could only study the islands from the deck of the vessel, as the natives were at that time in a very warlike humor. Dr. Becker in his report gives a brief summary of the previous work in Mindanao and the following is a quotation "Concerning the great Island of Mindanao, only scattered observations are available. Sainz de Baranda noted the occurrence of serpentine on the east coast of the island at Canmahat and in Misamis Province at Pigtao. Mr. Centeno states that at Pigholugan, near Cagayan, in the Province of Misamis, there are quartz veins in talcose schists. The auriferous districts of the Province of Surigao may, he points out, be regarded as a continuation of the Misamis district. The most notable deposits here are in the mountains of Canton, Ington, and Canmahat, a day's journey southward from the toast of Surigao. The terrane is here composed of much altered talcose slate and serpentine Mr. Semper collected on the Mantis, which is an upper tributary of the Agusan River in Surigao. Here he found a uralitic gabbro and a chloritized, aphanitie, augite-plagioclase rock, containing a few plagioclase phenocrysts. The specimens have been described by Mr. Oebbeke They are probably facies of the melaphyres found by Mr. Montano. Mr. Ashburner examined a slate belt in the extreme northern portion of the island, about 8 miles to the southward of the town of Surigao, at the headwaters of the Cansuran River. It contains auriferous quartz stringers. Mr. Montano collected melaphyres at a number of points in eastern Mindanao. Such are the eastern shore of the Bay of Butuan, the eastern coast of the island between Bislig and Catel, and the divide between the waters which flow northward into Butuan Bay and those which flow southward into the 'Gulf of Davao. The river of this southern drainage basin Montana terms the Sahug. Other authorities give it different names. In its headwaters he found float consisting of melaphyre Report on the Geology of the Philippine Islands, U. S. O. S. 21st An. Rep. (1899-1900), Pt. 3, 507. -He also mentions crystals of rutile from an island called Bigat, which is mknovn to me. Anal. d. Min, Madrid (1841), 2, 197-212. Memoria geologico-minera ( 1876 ) 49. 'Neues Jahrb. f. Mineral, etc. (1881), Beil-band 1, 498.