GE]?iEKA OF THE KoRTH AMERICAN PaLAEOZOIC BeYOZOA. 517 



the branches only two ranges of cell apertures, frequentl}^ sepa- 

 rated by a carina, and on the wider portion of the branches 

 three and occasionally more rans^es without a dividing ridge. 

 This genus has the same relation to Lykopora that Poltpobella 



has to POLTPOBA. 



Lyboporidri, no v. gen. 

 Type, Lyrojporidra subquadrans, Hall (sp.). 



(Plate 9, fig. 19.) 



This genus has the same general appearance and mode of 

 growth as Lybopora, but on the celluliferous face the cell aper- 

 tures are arranged in four parallel rows, two rows on each side 

 of a median carina or row of nodes. 



This genus bears the same relation to Ltropora that Fenistra- 



LIA does to POLYPOEA. 



Anastomopora, no v. gen. 

 Type, Anastomopora cinctuta, Hall (sp.). 

 (Plate 9, figs. 20-23.) 



This genus has a general resemblance to Lyropora, but the 

 branches are sinuous and anastoniosing ; cell apertures disposed 

 in three or more ranges, without separating carina. 



This genus bears the same relation to Lyropora that Ketepo- 

 EELLA does to PoLYPORA, and is separated from it by the fact that 

 the branches are connected by anastomosis, not by dissepiments. 



HELicopoRi, Claypole. 



(Quar. Jour. Geol. Soc, p. 30. 1883.) 



Type, Helicojpora latispiralis, Claypole. 



Original diagnosis. " Polyzoary expanded, fenestrate and spiral, 

 formed of slender, bifurcating rays, poriferous on one face, con- 

 nected by nonporiferous bars, forming an open network; cells 

 arranged in two rows along the rays, one on each side of a 

 median keel ; axis none, or consisting only of the thickened in- 



