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detached spicules of siliceous sponges, and occasionally some foraminifera.

Ser. I. Nos. 566, 567. Mount Rajoen. The rock is a compact, hard, greenish diabase-tuff apparently without lime, with a few, fairly well preserved radiolaria scattered through the matrix.

Ser. I. No. 584. Near Mount Rajoen. A compact, dark-gray, coarse grained tuff, giving a slight reaction in acid. Radiolaria are not numerous, but they frequently retain their structures.

Ser. I, No. 502. River Sëbëroewang, 1 km. above mouth of river Sajor. A soft, light-gray, finely granular, marly limestone. Radiolaria fairly numerous, their tests often preserved and infilled, sometimes with colloid silica, sometimes with calcite. They are of similar forms to those in the diabase-tuffs of the river Badoengan mentioned above. A few detached sponge spicules are also present. The only calcareous organisms recognizable are fragments of foraminifera.

Ser. II. Nos. 533, 536, 538, 546, 578. From different places on the rivers Tëpoewai and Gaang. Soft, gray to nearly black, very fine-grained, marls and marly limestones. Radiolaria very numerous, almost all in the condition of casts merely, but in some the walls are preserved. The tests are now filled with calcite. The forms are similar to those in the diabase-tuff, they principally belong to Cenosphcera and Cenellipsis and to the Discoidea. Rarely, Sphcerozoum spicules are present. There are a few acerate and cylindrical sponge-spicules, which, like the radiolaria, have been replaced by calcite. No calcareous organisms were seen in sections of this rock.

General Characters of the Radiolarian Rocks.

The jasper and chert or hornstone of the Plain of the Upper Kapoewas River are very hard and compact, and vary in tint from deep-red to greenish-gray, pellucid or milky-white. The rocks are, in nearly all the specimens examined, traversed in different directions by minute veins of quartz, sometimes to