. Bulletin - United States National Museum. Science. 158 BULLETI]Sr 7*7, UNITED STATES NATIONAL. MUSEUM. peristome around the sides and front margin, mm. wide and mm. in length. Fragments of this characteristic American Richmond species are not uncommon in the collections from the Lyckholm limestone. The delicacy of their branches, as well as the characters noted above, will distinguish these from all associated bryozoans. Occurrence.âGirardeau limestone division of the Richmond group, Alexander County, Illinois; Lyckholm limestone (Fl), Kertel, on the island of Dago, Esthonia (Cat.
. Bulletin - United States National Museum. Science. 158 BULLETI]Sr 7*7, UNITED STATES NATIONAL. MUSEUM. peristome around the sides and front margin, mm. wide and mm. in length. Fragments of this characteristic American Richmond species are not uncommon in the collections from the Lyckholm limestone. The delicacy of their branches, as well as the characters noted above, will distinguish these from all associated bryozoans. Occurrence.âGirardeau limestone division of the Richmond group, Alexander County, Illinois; Lyckholm limestone (Fl), Kertel, on the island of Dago, Esthonia (Cat. No. 57252, ). British Museum, one specimen from the Lyckholm limestone, Ker- tel, island of Dago. NEMATOPORA LINEATA (Billings). Text fig. 79. Eelopora Uneata Billings, Cat, Sil. Foss Anticosti, 1866, p. 36. Nematopora Uneata Ulrich, Geol. Surv. Illinois, vol. 8, 1890, p. 646, pi. 29, figs. 7-7e. Certain thin layers in the lower part of the Anticosti group on the island of Anticosti, Gulf of St. Lawrence, are crowded with fragments of a rather robust species of Nematopora described by Billings as Eelo- pora Uneata. Ulrich has figured the essential external and internal features of the species, referring it to his genus Nematopora. Speci- ^ mens indistinguish- able from this Ne- matopora are con- d "^ 7*^ i 'â \M' ^ tained in the solid limestone of the Borkholm forma- tion. Compared with other species of the genus, the branches of Nematopora Une- ata are quite stout, averaging a milli- meter in diameter. They are distinctly hexagonal in trans- verse section on ac- count of the zooecial arrangement in six rows separated by longitu- dinal ridges. The lineate appearance given the branch by these ridges is increased by the development of a second ridge, usually con- necting the zooecia. Measuring lengthwise, three and one-half zooecia occur in 2 Fig. 79.âNematopora lineata. a, fragment, natural size; b, sur- face OF SAME, X18; C, VERTICAL SECTION, X18; d AND C,
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