238 



BULLETIN 11, UISriTED STATES NATIONAL MUSEUM. 



species. The minutely granulosa wall structure determines the 

 generic position, although the granules are seldom clearly exhibited. 

 Dianulites petropolitana has a similar zoarium but its zooecia are a 

 third of a diameter less in size. 



4 



Fig. 133.— Dianulites grandis. a, the type-specimen, two-thikds natural size, in side view; 6, 



VIEW SHOWING SIMPLICITY OF STRUCTURE SEEN IN THE ORDINARY TANGENTLiL SECTION, X8; C, PORTION 

 OF THE SAME, X20, WITH THE GRANULES PLAINLY EXHIBITED ON THE WALLS OP A FEW ZOCECIA; d, TABU- 

 LATION IN VERTICAL SECTION, X8, CUTTING FOUR LAYERS OF ZOCECLi; C, SEVERAL TUBES OF A SINGIE 

 LAYER, X20, EXHIBITING THE TYPICAL DISTRIBUTION OF DIAPHRAGMS. LYCKHOLM LIMESTONE (Fl), 

 PlERSAL, ESTHONIA. 



Occurrence. — Apparently rare in the Lyckliolm limestone (Fl) at 

 Piers al, Esthonia. 



Holotype.—Csit. No. 57351, U.S.N.M. 



British Museum, thin sections and portion of the t^^pe-specimen. 



