. Bulletin de la Société géologique d'Amérique. La géologie. FOSSILIFEEOUS NODULES. 45 de la pyrite. Les spécimens de la poli extérieur shelly du nodule montrent qu'il contient une tendance à la plastification dans l'agencement des fragments plus ou moins modifiés, les plus grandes et natter les bords ou les visages de ces étant d'approximativement concentriques à la surface du nodule. Peut-être cette question apparemment très localisés lamellés ou une structure fibreuse se rapporte à la procédure Les modifications chimiques et mécaniques pari passu avec concrète- naire mouvements au cours de la solidification de la veine. Peut-être le plus inte

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. Bulletin of the Geological Society of America. Geology. FOSSILIFEEOUS NODULES. 45 of pyrite. Polished specimens of the shelly exterior of the nodule show that it contains a tendency to lamination in the arrangement of its more or less altered fragments, the larger and natter edges or faces of these being approximately concentric with the surface of the nodule. Possibly this apparently quite local laminated or fibrous structure is referable to chemical alterations proceeding pari passu with mechanical and concre- tionary movements during solidification of the vein stuff. Perhaps the most interesting thing about these nodules is that they contain remains of organisms. A polished portion of the rock revealed fragments of plants, as shown in figure 15. The three upper fossils are of black material, while the two lower forms are yellowish brown, in color. The latter may be seed cases, while those above appear to be termi- nals or bud-like extremities. Sir J. W. Dawson, to whom a drawing of the most perfect specimen was submitted, wrote that it was too small to deter- mine. While the black streaks seen in other fract ures of the vein mate- rial in proximity to these nodules in- dicate the presence of more fossils, the writer has as yet been unable to find anything determinable. The plant fragments figured do not occur in any individual bits of rock in the matrix of the vein, but evi- dently got into position among the rock fragments as bits of dead or living plants that were washed or fell into the gaping fissure during the process of filling. They are remnants of the vegetation of the period in which the clay-veins were made.. Figure 15.—Fossils from Nodules in Clay-vein. Magnified 5 times. Other Characteristics The clay-veins as proved and surveyed over about 2, 000 acres of mine workings in the Pittsburg seam, about 27 miles south of Pittsburg, Penn- sylvania, and bordering the Youghiogheny river, are observed to have no reference to or connection with (1) the dip o

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