n, 267.
----, and Mississippi, their junction recent, 264, 284.

Red Sea, level of, and of Mediterranean, 294.
----, coral reefs of, 777, 784.

Reefs, coral, outline destroyed by denudation, 795.

Refrigeration, Leibnitz's theory of, 26.
----, causes which might produce the extreme of, 106.

Reid, Col., on motion of shingle beaches, 320.

Rein-deer, geographical range of, 637.
----, migrations of, 640.
----, imported into Iceland, 686.

Rennel, Major, on delta of Ganges, 275.
----, on delta of Nile, 261.
----, on currents, 95, 97, 291, 292, 293.
----, on the tide-wave called "the Bore," 333.

Rennel, Mr., on delta of Ganges, 275.

Rennie, Rev. Dr., on peat, and fossils in peat, 718, 719, 720, 722.

Reptiles, their geographical distribution, 645.
----, their powers of diffusion, 645.
----, in carboniferous epoch, 136.
----, in Ireland, 645.
----, imbedded in subaqueous strata, 748, 771.
----, fossil, in old red sandstone, 135.
----, in coal, 136.

Rhine, R., description, of its course, 325.
----, its delta, 326.
----, tuff made of siliceous cases of infusoria, 388.

Rhinoceros, fossil, food of, 80.

Rhone, delta of, in Mediterranean, 258.
----, delta of, in Lake of Geneva, 189, 252, 286.
----, deposits at its confluence with the Arve, 288.

Rhone, a cannon in calcareous rock in its delta, 759.

Richardson, Sir J., on rocks near Mackenzie River, 115.
----, on sheep of Rocky Mountains, 598.
----, on distribution of animals, 640, 645.
----, on drift timber, in Slave Lake, 743.
----, on arctic fauna, 634.
----, on diffusion of fish, 647.
----, on isothermal lines, 94.

Richardson, Mr. W., on Herne Bay, 312.

Riddell, Dr., on sediment of Mississippi, 273.

Rive, M. de la, on terrestrial magnetism, 543.

River-ice, carrying power of, 219.

Rivers, difference in the sediment of, 189, 258.
----, sinuosities of, 205.
----, submarine, in Thessaly, &c., 357.
----, when confluent, do not occupy bed of proportionally larger
surface, 207.

Robert, M., on geysers of Iceland, 246.

Robertson, Capt., on mud volcanoes, 449.

Rockhall bank, recent deposits on, 778.

Rocks, specific gravity of, 206.
----, difference in texture of older and newer, 175.
----, altered by subterranean gases, 248.
----, origin of the primary, 176.
----, persistency of mineral character in, 157.
----, ol