SERTULARIAD.E. 



23 



arising at irregular distances (generally at the 

 angles of junction) out of a cellular basis, the 



apertures of the cells or spaces of which are often 

 themselves covered in by a lid perforated by a 



small tubular orifice. 



* 



C. arcta. Fig. 31** ; mag. 



\ 



Thuiaria (Flem.). As Sertularia, but the cells 

 are closely pressed to, or imbedded in, the surface 

 of the stem or branches. 



