. Bulletin - United States National Museum. Science. EAELY PALEOZOIC BEYOZOA OF THE BALTIC PROVINCES. 213 mesopores are often practically indistinguishable. The acanthopores are small but occur in such numbers in the mature zone that they give a minutely spinous or granular aspect to the zoarial surface. Thin sections show this to be a typical species of Stigmatella. Ver- tical sections exhibit thin, sUghtly crenulated tubes in the immature. Fig. 116.—Stigmatella inplecta. a, side view of the type-specimen, natueal size; 6, tangential SECTION, X20, WITH ONLY A SMALL POKTION CUTTING THE KEGION
. Bulletin - United States National Museum. Science. EAELY PALEOZOIC BEYOZOA OF THE BALTIC PROVINCES. 213 mesopores are often practically indistinguishable. The acanthopores are small but occur in such numbers in the mature zone that they give a minutely spinous or granular aspect to the zoarial surface. Thin sections show this to be a typical species of Stigmatella. Ver- tical sections exhibit thin, sUghtly crenulated tubes in the immature. Fig. 116.—Stigmatella inplecta. a, side view of the type-specimen, natueal size; 6, tangential SECTION, X20, WITH ONLY A SMALL POKTION CUTTING THE KEGION OF ACANTHOPORES; C, ANOTHER TAN- GENTIAL SECTION, X20, PASSING THROUGH A WELL-DEVELOPED ZONE OF ACANTHOPORES; d, SEVERAL ZOCECIA OF THE SAME SECTION, X40, WITH THE STRUCTURE OF THE WALLS AND ACANTHOPORES CLEARLY shown; C, VERTICAL SECTION, X20, SHOWING BOTH IMMATURE AND MATURE REGIONS. ORTHOCEEAS LIMESTONE (B3), PORT KUNDA, ESTHONXA. region. These thicken somewhat in the mature zone with the devel- opment of numerous acanthopores. The latter region is further dis- tinguished by having an occasional diaphragm in the mesopores. Tangential sections vary in appearance according to the zone which is cut. In figure 116 &, the section passes through portions of both the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States National Museum; Smithsonian Institution; United States. Dept. of the Interior. Washington : Smithsonian Institution Press, [etc. ]; for sale by the Supt. of Docs. , U. S. Govt Print. Off.
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