Evactinopora
radiata
Proceedings of the Academy of Natural Sciences
Philadelphia
1865
Genus Evactinopora, M. & W.
Evactinopora radiata, M. & W.
The interesting fossil upon which we propose to found this genus and species is entirely silicified, and , as seen from below, presents the form of a regular eight-rayed star, the rays being slender, and nearly equalling [sic] in length the diameter of the nucleus. In a side view, however, it is seen to be regularly rounded in outline below, while the slender rays are observed to be produced upwards in the form of thin vertical laminae, which converge to the centre [sic] over the nucleus. The specimen is not in a condition to show whether or not there is a central axis extending all the way up, but there probably is. The rays are thickest below, and taper gradually upwards on their outer margins, which are beveled or carinated all the way down to where they meet at the middle of the under side. Within, they each pass abruptly into a thin lamina, which is poriferous on both sides, and extends to the middle over the nucleus.
The pores are circular, with a slightly prominent margin, and regularly disposed nearly in quincunx, at intervals about equalling [sic] their own diameter, or sometimes less. They only exist in the thin portion of each ray, while the thicker outer and inferior portions seem to be nearly or quite solid.
We are not able to determine satisfactorily whether this was a free or an attached Bryozoan; but if attached, the stem or point of attachment was probably very small.
Greatest transverse diameter to the extremity of the rays, 9.90 inch; do. Of nucleus between the rays, 035 inch; thickness of the outer margin of each ray near the nucleus, 0.10 inch; diameter of pores about 0.02 inch.
Locality and position -- The only specimen of this fossil we have seen is in a granular mass of decomposing chert, containing some fragments of small crinoid columns. It was obtained from the Subcarboniferous rocks of Missouri, but the exact locality and position we have been unable to ascertain.
Reference:
Meek, F. B., and Worthen, A. H., 1865, Notice of some
New Types of Organic Remains, from the Coal Measures of Illinois, Proceedings
of the Academy of Natural Sciences of Philadelphia