EAELY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 



79 



tions by a slight thickening of the wall. The cell walls are unusually 

 contorted in the macular spaces, which, as shown in figure 20 a, are 

 composed almost entirely of mesopores. Vertical sections show the 

 usual short, immature region with thin walls bending gradually into 

 the thick walled mature zone. Diapliragms are absent in aU of the 

 sections studied. 



The incrusting zoarium, thick-walled, irregularly rounded zooecia 



Fig. 20.— Ceeamopora invenusta. a, tangential section, X20, through a macula and neighboe- 



ING ZOCECIA; 6, tangential section, X20, SHOWING THE lEEEGULAB ZOCECTA AND NUMEEOUS GRANULES 

 OR ACANTHOPOEES; C, VERTICAL SECTION, X20, THEOUGH A ZOARIUM EXHIBITING THE CHARACTERISTIC 

 COMMXINICATION PORES. WESENBERG LIMESTONE (E), WESENBERG, ESTHONIA. 



with large granular structures, indenting the aperture, gives an aspect 

 to the present form quite different from any other species of the genus. 



Occurrence. — Not uncommon in the Wesenberg limestone (E) at 

 Wesenberg, Esthonia. 



Holotype.—C&t. No. 57190, U.S.N.M. 



A fragment of the type-specimen and thin sections are in the collec- 

 tions of the British Museum. 



CERAMOPORA INTERCELLATA, new species. 



Plate 6, fig. 2; text fig. 21. 



Externally this new form has less resemblance to Ceramopora than 

 the two species just described; but thin sections bring out the char- 

 acteristic ceramoporoid structure, and especially nunaerous connect- 

 ing mural pores. The type-specimen is a flat, epithecated expansion, 

 consisting of two superposed layers of zooecia, as shown in figure 21a. 

 The ceUuliferous face bears the apertures of large polygonal zooecia, 

 nearly always completely isolated by numerous irregularly polygonal 

 mesopores. The poriferous side is smooth, but exceptionally large 



