tore the solid rocks from their original beds, from the general level of the surrounding summits, down to the present bottoms of the lakes. Oneida and Onondaga lakes occupy level land in the northeast part of the Oswego Basin. Mud Creek, the most westerly branch of the Oswego River, takes its rise in Ontario County, flows northeast into Wayne County, where it unites with Canandaigua Outlet and takes the name of Clyde River; then it flows east to the west line of Cayuga County, where it empties into the Seneca River. This latter stream, made up of the outlets of Seneca and Cayuga Lakes, from this point flows in a northeasterly course, and receives successively the outlets of Owasco, Skaneateles, Onondaga, and Oneida lakes. From the mouth of the last-named stream it takes the name Oswego River, and its course is nearly due north to Lake Ontario. The fourth subdivision includes the streams flowing into Lake Ontario and the St. Lawrence River east of the mouth of the Oswego. The principal of these are the Salmon, Black, Oswegatchie, Grasse, and Raquette rivers. The water is usually very dark, being colored with iron and the vegetation of swamps. The fifth subdivision includes all the streams flowing into Lakes George and Champlain. They are mostly mountain torrents, frequently interrupted by cascades. The principal streams are the Chazy, Saranac, and Ausable rivers, and Wood Creek. Deep strata of Tertiary clay extend along the shores of Lake Champlain and Wood Creek. The water of most of the streams in this region is colored by the iron over which it flows. The second general division of the river system of the state includes the basins of the Allegheny, Susquehanna, Delaware, and Hudson. The Allegheny Basin embraces the southerly half of Chautauqua and Cattaraugus counties and the southwest corner of Allegany County. The Allegheny River enters the state from the south in the southeast corner of Cattaraugus County, flows in nearly a semicircle, with its outward curve toward the north, and flows out of the state in the southwest part of the same county. It receives several tributaries from the north and east. These streams mostly flow in deep ravines bordered by steep, rocky hillsides. The watershed between this basin and Lake Erie approaches within a few miles of the lake, and is elevated above it. The Susquehanna Basin occupies about one-third of the south border