Genera of the North American Palaeozoic Bryozoa. 599 



an imaginary axis; apertures prominent, circular, arranged in 

 a transverse series or spirally around the stem ; walls thin. 



206 2051 



Fig. 205. Mitoclemacinctosum, natural size. 

 Fig. 206. A portion of the same, xl8. 



Family Reptaridse. 



This family includes those adnate forms, having a central axis 

 and bilateral tubular cells. The following genera are included 

 in the family : Hederella and Reptaeia. 



Hederella, Hall. 

 (Trans. Albany Institute, Yol. X, p. 194. 1881.) 

 Type, Hederella Canadensis^ Billings. 



(Plate 25, figs. 10-13.) 

 Zoarium parasitic, procumbent, attached its entire length; 

 usually occurring on corals or Brachiopoda. Zoarium consisting 

 of a primary, cylindrical, tubular axis, which has bilateral 

 tubular cells at frequent intervals and occasionally cells having 

 the same manner of growth as the primary axis. This manner 

 of growth is indefinitely continued so that comparatively large 

 surfaces are covered by the fronds; cells subcylindrical with 

 transverse annulations and striations, and also fine longitudinal 

 striations ; cell tubes in contact with the axis for a portion or 

 the whole of their length. 



Rbptaria, Rolle. 



(Leonhard and Bronn, ITeues Jahrbuch, p. 180. 1851.) 



Type, Beptaria stolonifera^ Bolle. 



(Plate 25, figs. 8, 9.) 



Zoarium adnate, consisting of a rachis, from which proceed, 

 laterally, simple cell tubes, and, at irregular intervals, tubes 



