CYCLOSTOMATOUS BRYOZOA — CANU AND BASSLER. 



95 



peristome is little salient. The mesopores are irregular; they ara 

 rather short and narrow. 



In tangential section the mesopores appear to be of a smaller 

 diameter than the tubes and their arrangement is quite variable. The 

 annular canal formed by the parietal vesicles is quite thin. 



The mesopores are closed by a very fragile calcareous lamella and 

 specimens with it intact are very rare. The peristome is hardly 

 salient; it is sometimes quite visible. 



A C 



Fig. 23. — Ripisoecia conifera Lamouroux, 1821. 



A. Longitudinal section, X 16, showing tbe vesicular walls of the recurved 

 portion. 



B. Tangential section, X 16. 



C. Transverse section, X 16. 



Jurassic (Bathonian) : St. Aubin (Calvados), France. 



Occurrence. — Jurassic (Bathonian) : St. Aubin (Calvados), France. 

 Plesiotypes.—Canu collection and Cat. No. 68942, U.S.N.M. 



GRAMMECAVA, new genus. 



(Greek; gramme., line in allusion to the black median line of thin 

 sections. ) 



The tubes are short, with triparietal gemmation, without peri- 

 stome; their recurved extremity is much widened and has vesicular 

 walls ; they are often closed by a facette bearing an operculate aper- 



