Genera of the ^N'orth American Palaeozoic Bryozoa. 525 



Figs. 74 and 75 are photo-engravings from King's original 

 illustrations. 



Fig. 74. Thamniscus dubius, natural size. 

 Fig. 75. Celluliferous face of same, enlarged. 



Thamnooklla, nov. gen. 

 Type, Thamnocella Cisseis, Hall (sp.). 

 (Plate 9, figs. 4-12.) 



Zoarium ramose, sometimes f ruticose ; giving off lateral branches 

 or bifurcating; branches of equal size, and, compared with Tham- 

 niscus infrequent ; cells numerous ; arranged in quincunx order, 

 forming oblique transverse rows. 



This genus differs from Thamniscus in the infrequency of the 

 branches, and in the fact that the branches are of uniform size; 

 from some forms of Diplopoka in having numerous cell apertures, 

 that genus having but two ranges. 



DiPLOPORA, Young and Young. 



(Proc. Nat. Hist. Soc. Glasgow. 1875.) 



Type, Dijplopora marginalis, Young and Young. 



Very slender straight stems, throwing off a few lateral branches 

 of equal dimensions (or bifurcating) ; celluliferous face with two 

 ranges of cell apertures, and moderately developed median keel ; 

 noncelluliferous face striated. 



