Genera of the E'orth American Palaeozoic Bryozoa. 581 



MuNoiRYPA, Nicholson. 



(Pal. Tab. Corals, p. 320. 1879.) 



Type, Monotrypa undulata^ Nicholson. 



Zoarium irregularly massive, discoidal, subglobose or hemi- 

 spheric. Cell tubes polygonal, prismatic, and very thin through- 

 out their entire length, and often undulating or wrinkled 

 transversely ; diaphragms remote or entirely wanting, except 

 near the surface. 



15S 



— 







H 



Fig. 151. Monotrypa rectimuralis, natural size. 

 Fio. 152. Transverse section, xl8. 

 Fig. 158. Vertical section, xl8. 



Monotrypella, Ulrich. 

 (Jour. Gin. Soc. Nat. Hist., Yol. Y, p. 173. 1882.) 

 Type, Monotrypella cequalis, Ulrich. 



Zoarium ramose, branches cylindrical or flattened ; cells 

 tubular, polygonal, arising from the center of the branch, and 

 more or less regularly curving to the surface. For the greater 



