48 BULLETIN 77, UNITED STATES NATIONAL MUSEUM. 



Vesicular tissue. — In a number of forms tlie space between the 

 zooecia is occupied by tissue composed of irregularly superimposed 

 vesicles. This probably served to give strength to the zoarium and 

 to protect the zocEcia. 



Acanthofores. — Small cylindrical tubes usually situated at the 

 angles of junction of adjoining zocecia, forming spinelike projections 

 upon the surface. Thin sections show that the acanthopore is not a 

 mere surface ornament but is a tube inclosed in the w^all substance of 

 the zooecium and developed generally only in the mature region. 

 This tube, with its inclosing wall substance, sometimes reaches a size 

 as great as that of the ordioiary mesopore. 



Lunarium. — In the Ceramoporidse and Fistuliporidse especially, 

 the posterior portion of the zocecial wall is more or less thickened and 

 elevated above the general surface and curved to a shorter radius to 

 form the crescentic structure known as the lunarium. 



BIBLIOGRAPHY. 



Although the list of articles dealing with the Russian Ordovician 

 Bryozoa is not a small one, practically all of A^alue that has been pub- 

 lished is contained in Dybowski's " Chaetetiden der OstbaltischenSilur- 

 Formation " and in Eichwald's "LethseaEossica." As neither of these 

 works is easily obtained, the illustrations and some of the observa- 

 tions of both authors have been incorporated in the present work, in 

 the effort to embody in this volume all available information regarding 

 the subject. The following list is believed to contain most of the 

 publications referring to the Russian Ordovician Bryozoa : 



LIST OF PUBLICATIONS. 



1825. EiCHWALD, Edouard von. Geognostico zoologicte per Ingriam marisque Bal- 

 tic! provincias nee non de Trilobitis observationes. 



1829. Zoologia Specialis, vol. 1, pp. 179-180, 198-201, pis. 2, 3. 



1830. Pander, C. H. Beitrag zur Geognosie d. Russlands. 



1833. GoLDruss, August. Petrefacta Germanic, vol. 1, pp. 23-41, pis. 8-12. 

 1837. KuTORGA, S. Zweiter Beitrag zur Paleontologie und Geognosie Dorpats. 

 1840. EiCHWALD, Edouard von. tjber das Silurische ScMchtensystem von Esth- 



land. 

 1840-1842. Die Urwelt Russlands durch Abbildungen eriautert, pt. 1, pp. 



1-106, pis. 1-4; pt. 2, pp. 1-184, pis. 1-4. 

 1842. KuTORGA, S. Verhandlungen der mineral Gesellschaft zu St. Petersburg. 



1845. Lonsdale, William. Description of some charac teristic Paleozoic Corals of 



Russia, in Verneuil and Keyserling's Geology of Russia in Europe and the 

 Ural Mountains. [Bryozoa, pp. 626-632.] 



1846. Keyserling, Alexander von. Wissenschaftliche Beobachtungen auf einer 



Reise in der Petscbora-Lande im Jabre 1843. 

 1851. Milne-Edwards, Henri, and Haime, Jules. Monograpbie des polypiers fos- 

 eiles des Terrains Palaeozoiques. 



