EAELY PALEOZOIC BEYOZOA OF THE BALTIC PROVINCES. 299 



Other sections, even from the same specimen, show ±10 diaphragms at 

 all. This has required a sUght emendation in the original diagnosis 

 of the genus. 



The zoarium of AnapTiragma mirahile is of smooth, strong, sub- 

 cyhndrical branches, 8 to 10 or more milhmeters in diameter, divid- 

 ing rather frequently. Maculae not a conspicuous feature; distin- 

 guished only by the size of their zooecia, which are somewhat larger 

 than the average. Zooecial apertures angular to subangular, with 

 rather thick walls, five to six zooecia in 2 mm, ; mesopores smaU and 

 comparatively few in number; acanthopores small and seldom well 

 shown at the surface, although when observed they show the usual 

 apical perforation. 



In vertical sections the striking feature is the almost complete 

 absence of diaphragms in both the zooecia and mesopores. In the 

 axial region the walls are thin and wavy, the crenulations being long 

 and not so frequent as in species of Calloporina, a somewhat similar 

 genus of the Halloporidse. With the inception of the mature region, 

 the walls become greatly thickened and considerable laminated tissue 

 is developed upon the inner sides. Tangential sections show the 

 zooecial walls to be of considerable thickness and to have the charac- 

 teristic structure of Batostoma. The acanthopores are seen to be 

 small, few in number, and situated at the junction angles. 



The rather large angular zooecia, thick walls, and few mesopores, 

 and, more satisfactorily, the crenulated tubes with their practical 

 absence of diaphragms, distinguish this species from otherwise 

 similar associated forms. 



In the thin sections shown in figure 183 & and c, the acanthopores 

 and the dark line separating adjoining zooecia are especially well 

 developed. 



Occurrence. — The species is a characteristic fossil of the Fernvale 

 limestone division of the Richmond group in the JVIississippi Valley, 

 the type-locahty being Wilmington, Illinois. The Russian examples 

 of the species were found in the upper part of the Lyckholm limestone 

 (Fl) at Kertel, and at Hohenholm on the island of Dago. 



Plesiotype.— Cat. No. 57385, U.S.N.M. 



Represented in the collections of the British Museum by American 

 specimens. 



ANAPHRAGMA MIRABILE COGNATA, new variety. 



Text fig. 184. 



Zoarium ramose with branches subcyhndrical, frequently dividing, 

 and 6 to 8 or more millimeters in diameter; maculse not a conspic- 

 uous feature of the surface, which is smooth. Zooecial apertures 

 polygonal with rather thick walls. Five zooecia in 2 mm. Mesopores 

 few and small, acanthopores small and sometimes numerous but not 

 conspicuous at the surface. 



92602°— Bull. 77—11 ^21 



