134 NE W YORK STATE MUSEUM 



Distinguishing characters. Form circular or cup-shaped in grow- 

 ing state; thin, flat, frequently bifurcating branches, united laterally 

 by obliquely transverse filaments, leaving oblong quadrangular in- 

 terstices; indented or obliauely and intermittently striated surfaces. 



Fig. 27 Dictyonema retiforme 



Found rarely in the lower part of the Rochester shales in the 

 Niagara section; usually fragmentary. Abundant at Lockport and 

 elsewhere. (Hall) 



Genus stromatopora Goldfuss 



[Ety.: a-pmij.a, a covering; x6po<s, a pore] 



(1826. Pctrcfacta Gcrnianiac, p. 22) 



Skeleton forming hemispheric, globular or expanded masses com- 

 posed of numerous concentric, undulating calcareous laminae, separ- 

 ated by interspaces, and connected by radial pillars which unite 

 with the thick concentric laminae and form a finely reticulate tissue, 

 visible in cross-section. Traversing the entire mass are sparsely 

 scattered tubes which are divided by numerous tabulae or horizontal 

 floors, and were occupied by the larger polyps of the colony. Base 

 of entire skeleton covered by a» wrinkled " epitheca ". 



Stromatopora concentrica Goldfuss Hall (Fig. 28) (1852, Pal. 

 N. Y. 2:136, pi. 37) 



Distinguishing characters. Hemispheric or spheroidal form some- 

 times irregular; thin concentric laminae, readily visible in weathered 

 specimens, and scarcely of the thickness of writing paper; surface of 

 laminae marked by fine pores. 



