EAKLY PALEOZOIC BEYOZOA OF THE BALTIC PROVINCES. 317 



Esthonia; Jewe limestone (Dl), St. Mathias, Baron Toll's estate, and 

 Paesklill, Esthonia; Kegel limestone (D2) Kegel, Esthonia; Wassa- 

 lem beds (D3), Uxnorm, Esthonia; Wesenberg limestone (E), Wesen- 

 berg, Esthonia; Lyckholm limestone (Fl), Lyckholm and Lechts, 

 Esthonia, and Hohenholm, Kertel, Paope, and Keilo, island of Dago. 



Plesioty pes. —Csit. Nos. 57430 to 57449, U.S.N.M. 



British Museum, specimens and thin sections from various localities 

 in Russia, and the island of Oeland. 



DIPLOTRYPA BICORNIS (Eichwald). 



Plate 5, figs. 3-3(/; text figs. 196-198. 



Dianulites bicomis Eichwald, Zool. spec, vol. 1, 1832, p. 181, pi. 2, fig. 15. 

 Chsetetes heterosolen Keyserling, Beobachtungen avif einer Reise in das Pet- 



echora-Land, 1846, p. 181, fig. a, b. — Edwards and Haime, Monogr. des 



polyp, foss., 1852, p. 273. 

 Monticulipora heterosolen Schmidt, Archiv. fur Naturk. Liv-, Ehst- und Kurlands, 



vol. 2, eer. 1, 1858, p. 228. — Milne-Edwards, Hist. nat. des Cor., vol. 3, 



1860, p. 274. 

 Ceriopora bicomis Eichwald, Lethsea Rossica, vol. 1, sec. 1, 1860, p. 413, pi. 25, 



fig. 3. 

 Callopora heterosolen Dybowski, Die Chaetetiden der Ostbaltischen Silur-For- 



mation, 1877, p. 119, pi. 4, figs. Sa-d. 

 Cfr. Diplotrypa limitaris Ulrich, Geol. and Nat. Hist. Surv. Minnesota, vol. 3, 



pt. 1, 1893, p. 286, fig. 18. 



Commencing in the Glauconite limestone and continuing through 

 the Wassalem beds is a species of Diplotrypa equally as abundant as 

 the associated D. petropolitana and HaUoporaf dyhowskii. This species 

 was first described by Eichwald as Dianulites licornis, his illustra- 

 tions being presented 

 below as figure 196. 

 Dybowski gave a full 

 description and nu- 

 merous figures of the 

 species, but adopted 

 Keyserling's specific 

 name Tieterosolen, for 

 the reason that the 

 term hicornis was ap- 

 plicable to only a par- 

 ticular form of growth. 

 Although this is true, 

 the rules of nomencla- 

 ture demand the use 

 of the earher name 

 adopted above. 



Although extremely variable in form, the zoarium of Diplotrypa 

 hicornis is massive and more or less hemispheric. Young specimens 

 are regularly hemispheric in shape with a wrinkled epithecated base 





b 



Fig. 196.— Diplotetpa bicoenis. a, AN example of the usual 



FORM, NATURAL SIZE; 6 AND C, TWO VIEWS OF THE SURFACE, EN- 

 LARGED. Copied from Eichwald's figures of Ceriopora 

 BICORNIS. "Calcaire A. Orthoceratites," Pulkowa, govern- 

 ment OF St. Petersburg. 



