SYNOPSIS OF GENERA. 



XXI 



Examples: Stidopora Gilberti, pi. xxvii, figs. 20-35; pi. xxviii, figs. 21, 22. 

 Stidopora indsurata, pi. ix, figs. 1-18. 



Thamnotrypa, n. g. [Type, Thamnopora divaricata, Hall.] 



Zoarium consisting of a main branch or stipe, from which proceed lateral 



branches at nearly right angles to the main stem, celluliferous on both sides. 



Cells arising from a mesotheca. Apertures disposed in two ranges on the 



branches, and in three or sometimes four ranges on the main stipe. 

 Example : Thamnotrypa divaricata, pi. xxxiii, figs. 9, 10. 



Taeniopora, Nicholson (Palaeontology of Ontario, p. 108. 1874). 

 [Type, Taeniopora exigua, Nicholson.] 



Zoarium ramose, branches triangular or flattened, celluliferous on each face. 

 Cells cylindrical, proceeding from laminae which radiate from the center to 

 each angle of the branch, or from a simple mesotheca in the flattened branches. 

 Intercellular tissue vesiculose. 



Example : Taniopora exigua, pi. Ixii, figs. 15-26. 



Prismopora, Hall (Trans. Albany Institute, vol. x, p. 158. 1881). 



[Type, Prismopora triquetra, Hall.] 



Zoarium ramose, consisting of triangular branches, frequently forming irreg- 

 ular groups. Branches with the sides equal or unequal, concave ; celluliferous 

 on each side. Cells tubular, arising from mesial plates which extend from the 

 center of the branch to each tangle. Intercellular tissue vesiculose. 



Examples: Prismopora triquetra, pi. xxviii, figs. 8-10; pi. xxix, figs. 9-15. 

 Prismopora dilatata, pi. Ixii, figs. 13, 14. 



Scalaripora, Hall (Tran. Albany Institute, vol. x, p. 159. 1881). 

 [Type, Scalaripora scalariformis. Hall.] 



Zoarium consisting of groups of triangular prismatic branches, celluliferous 

 on each face. Sides of branches concave and crossed by transverse, elevated, 

 celluliferous scalae. Cells tubular, arising from the radiating mesothecae of the 

 branches and from the mesothecae of the scalae. Margins of branches and 

 scalae non-celluliferous. 



Examples : Scalaripora scalariformis, pi. xxix, figs. 4-8. 

 Scalaripora subconcava, pi, xxix, figs. 1-3. 



