1. Senecas on the Allegheny river, in Pennsylvania, fifteen miles above Warren, at CORNPLANTER'S town, (Jennesadaga.) Population 80 Acres of land owned 300 2. Senecas on the Allegheny reservation, in New York, a few miles above the Pennsylvania line. Population about 900 Acres of land 26,600 3. Senecas on Cattaraugus reservation, in Erie and Cattaraugus counties, New York. Population about 1,700 Acres of land under cultivation 5,000 4. Senecas at Tonnawandas, in New York. Population about 700 Acres of land 7,000 ONEIDAS. 1. Oneidas, in Oneida and Madison counties N. York. Population about 250 Acres of land 400 2. The largest remnant of this tribe, (Oneidas,) reside in Brown county, Wisconsin. Population about 800 They possess a large body of land. ONONDAGOS. The residence of this tribe is about six miles south of the city of Syracuse, in the State of New York. Population about 350 Acres of land owned 7,600 TUSCARORAS. Their residence is about seven miles north-east of Niagara Falls. Population about 350 Acres of laud held by them 6,250 RECAPITULATION OF POPULATION. Senecas 3,380 Oneidas 1,050 Onondagos 350 Tuscaroras 350 ----- Total 5,130 The present condition of these remnants of the Six Nations is quite respectable. In most of the reservations they have schools and places of public worship. Many of them belong to the Methodist and Baptist churches. The Chief of the Six Nations, STEPHEN S. SMITH, who made a speech at the inauguration of the CORNPLANTER monument, is a minister in the Baptist church. He is a man of intelligence and respectability, I here insert a letter I have recently received from him, which will doubtless be interesting to our readers. "AKRON, N Y., _July 10, 1867_.