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PROCEEDINGS OF THE NATIONAL MUSEUM. 



tion in this respect. The geologic distribution given by Gregory ap- 

 pears to be erroneous. 



Fig. 27. — Ditaxia auomalopora Gohlfuss, 1827. 



A. Transverse section, X 16, with the median lamella almost rectilinear. 



B. A similar section, X 16, with undulated median lamella. 



C. A meridian section, X 16, cutting just above the median lamella. 



D. Typical longitudinal section, X 16, showing the short tubes. 



E. Another longitudinal section, X 16, showing a unilamellar expansion com- 

 mencing to cover the frond. 



F. Tangential section, X 16, illustrating zooecia and thick walled mesopores. 



G. Portion of a longitudinal section of well developed frond, X 16, exhibiting 

 the vesicular wall structure. 



Cretaceous (Maastrichtian) : Maastricht, Holland. 



Stmicture. — We have not yet had the good fortune to discover an 

 ovicell of this species well enough preserved to be photographed, but 

 its place in the family Leiosoeciidae appears to us not to be doubted. 



