. Bulletin of the Geological Society of America. Geology; Geology -- United States. J. F. JAMES—THE GENUS SCOLITHUS. 37 ized to accept the positiveness of its evidence, because (1) of its anomalous char- acter; (2) because it is found in a metamorphic rock, and may, therefore, have been altered from some other species of organism, considerably different from the orig- inal of the Scolithus. For instance, upon the supposition that the quartz rock is middle Silurian, we should imagine the Fucoides rcrticalis of the neida conglom- erate would change into a form not distinguishable from the Scolit
. Bulletin of the Geological Society of America. Geology; Geology -- United States. J. F. JAMES—THE GENUS SCOLITHUS. 37 ized to accept the positiveness of its evidence, because (1) of its anomalous char- acter; (2) because it is found in a metamorphic rock, and may, therefore, have been altered from some other species of organism, considerably different from the orig- inal of the Scolithus. For instance, upon the supposition that the quartz rock is middle Silurian, we should imagine the Fucoides rcrticalis of the neida conglom- erate would change into a form not distinguishable from the Scolithus ; This "quartz rock" is now regarded by Walcott as of lower Cambrian age. The figure given by Hitchcock is not distinguishable from Scolithus verticalis, Hall (& clintonensis of this paper). In the same year Mr. E. Billings* referred to S. linearis as occurring in the sand- stone at l'Anse au Loup, strait of Belle Isle, differing from the common form of the Potsdam of Canada, but being identical with that of the upper Primal of Pennsyl- vania, and with that of the Potsdam of Tennessee (Number III of Safford). Bil- lings then regarded the form as a plant. The rock at l'Anse au Loup is now considered to be of lower Cambrian age. In the same volume f appears a description of a new species, under the name of Scolithus canadensis. It consists of cylindrical or irregularly prismatic stems (or rather the cavities in the rock once occupied by such stems) " from 1 to 2 lines in diameter and from 1 to 6 inches in length, and either straight or more or less curved. In some specimens several of the stems are in contact with each other, and when this is the case and the stems have an angular shape they very much resemble the coral Tetradium. The larger stems are more often straight than the smaller. The true Scolithus linearis is generally larger and the stems straight and parallel with each other. It occurs in the upper Potsdam of Canada and on the ea
Size: 1710px × 1461px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorge, booksubjectgeology, booksubjectgeologyunitedstates
