Genera of the Xorth America:n- Palaeozoic Bryozoa. 605 



ADDENDUM. 



Stiotopoea, Hall. 

 (Pal. N. Y., Yol. I, p. 73. 1847.) 

 Type, Stictopora elegantula, Hall. 



(Plate 10, figs. 9, 10, 20.) 

 Zoarium attached by a spreading base to foreign objects; 

 ramose; branches thin, transverse section lenticular; composed 

 of two layers of cells separated by a mesotheca; cell apertures 

 circular or oval, surrounded by a peristome; rows of cells fre- 

 quently separated by narrow ridges; margins noncelluliferous; 

 interapertural space vesiculose or apparently solid. 



This genus differs from CYsroDicTYA principally in the absence 

 of pseudo septa and lunaria. 



Aetheopoka, Ulrich. 

 (Jour. Cin. Soc. Kat. Hist., Yol. Y, p. 152. 1882.) 

 Type, Arthropora Shafferi^ Ulrich. 



'' Zoarium jointed; segments short, with several branches pro- 

 jecting from each edge, some of which may or may not be tipped 

 for articulation with succeeding segments; cell mouths sub-circu- 

 lar, separated by interstitial pits or sulci." 



Khinidictya, Ulrich. 

 (Jour. Cin. Soc. Nat. Hist., Yol. Y, p. 152. 1882.) 

 Type, Bhinidictya Nicholsoni^ Ulrich . 

 (Plate 10, figs. 3-5„) 

 " Zoarium narrow, branching at long intervals; cells surrounded 

 by a close series of spiniform tubuli." 

 Yery similar to Stictopoea. 



Ptilocella, nov. gen. 

 Type, Ptilocella jparallela^ Hall (sp.). 



(Plate 15, figs. 1-3.) 

 Zoarium ensiform ; in its pointed, striated base resembling 

 P'liLODicTYA, but the cell apertures are circular, arranged in par- 



