EAELY PALEOZOIC BRYOZOA OF THE BALTIC PROVINCES. 233 



the confusion that this has caused is so great that in most cases it is 

 best to disregard such references altogether. In the above list but 

 a single reference to petropolitana is of undoubted value, and only the 

 work of those authors who might have included the species here 

 described as Dianulites petropolitana is cited. More than a dozen of 



4..„4 





Fig. 129. — DiANUUTES PETEOPOLITANA. a, the typical FOEM of the species as seen m TANGENTIAL 

 SECTION, X20; 6, VEETICAL SECTION, X8, SHO"WING DISTEIBITTION OF DIAPHEAGMS,- C, SEVEEAL TUBES 

 OF THE SAME, X20, "WITH THE MINUTE STEUCTUEE MOEE CLEAELT EXHIBITED. GLAUCONITE LIMESTONE 

 (B2), DXJBOVIKI, GOVEENMENT OF St. PETEESBUKG. 



the Russian Ordovician trepostomatous bryozoans have the zoarial 

 shape of this species, so, without a knowledge of the minute structure, 

 it is obviously impossible to determine which particular one Pander, or 

 any of the other authors except Dybowski, had in mind. Indeed, it 

 is most probable that they included a number of distinct species in 

 their descriptions. 



