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NEW YORK STATE MUSEUM 



Edwards and Haime {Monographie des polypiers fossiles. 1851. 

 p. 418), in the description of Acervularia davidsoni, 

 speak of the interior wall, but those forms which in this country 

 have been generally considered as A. davidsoni do not have 



45 



Fig. 43 Prismatophyllum (davidsoni) E. and E. Trans- 

 verse section showing prismatic form, the septa, and the cut margins of 

 cysts, enlarged 



44 P. r u g o s u m i/. and H. Transverse section showing polygonal 

 form of corallites and denticulated septa, enlarged 



45 Longitudinal section showing internal structure 



an interior wall, though in a transverse section the abrupt ending 

 of the cysts, or dissepiments, coincidentally with the shorter 

 septa gives the appearance of an interior wall. The continuation 

 of alternate septa to the center proves that there is no secondary 

 wall. 



