44 



NORTH AMERICAN INDEX FOSSILS. 



VI. Stromatopora Goldfuss. 



Massive or laminar. Laminae grouped in strata or "latilaminae"; 

 radial pillars numerous, extending across a stratum and uniting with 

 the laminae to form a finely retic- 

 ulated tissue as seen in vertical 

 section. Tabulate zooidal tubes, 

 and astrorhizae present. Syring- 

 ostroma differs chiefly in its denser 

 structure and somewhat more dis- 

 tinct horizontal and vertical ele- 

 ments. Silur. (rare)-Devonic. 



13. S. antiqua Nicholson & Murie. 



(Fig. 70.) Siluric. 



Massive, spheroidal or hemis- 

 pheric, with well-marked strata or 

 latilaminae5 or 6 to 1 cm. Delicate 

 zooidal tubes traversing entire 

 stratum. Astrorhizal centers 4-5 

 mm. apart, mamelons absent. 



Niagara limestone of Canada 

 and New York. 



14. S. (Ccenostroma) monticuli- 



fera Winchell. Devonic. 



In large hemispheric or globu- 

 lar masses, surface with large ma- 

 melons and astrorhizae ; centers 

 7.6 to 10 mm. apart. Extremely abundant in the Traverse (Ham- 

 ilton) group of Michigan. 



15. S. pustulifera Winchell. Devonic. 

 Similar to preceding, but surface with pustules instead of mame- 

 lons and smaller astrorhizal centers, 4 mm. apart. 



Occurs with the preceding. 



16. S. (Syringostroma) densa Nicholson. (Fig. 71.) Mid- 

 Devonic. 



Surface without mammillae but well developed astrorhizae. 

 Structure exceedingly dense. 



Onondaga of Ohio and probably elsewhere. 



FlG. 70. Stromatopora antiqua, ver- 

 tical sections, the lower, X 2 (after 

 Nicholson). 



