HYDROCORALLINES— STROM ATOPOROIDEA. 43 



tant rounded mamelons pierced by apical pores, and with astro- 

 rhizae inconspicuous. Surface covered with granules. 

 Common in the Hamilton formation of Canada. 



10. S. tuberculata Nicholson & Murie. (Fig. 67, 68.) 



Mid-Devonic. 

 Differs from the preceding in absence of mamelons, the surface 

 being undulating and covered only with tubercles of two sizes, and 

 in coarser meshwork (about 6 laminae to 2 mm.). 



FlG. 68. Stromatoporella tuberculatum- Fig. 69. Stromatoporella incrustans 

 larged surface and section (after Nicholson). (N. Y. State Mus. Rep.). 



In the Onondaga limestone of Canada and Ntw York. 



11. S. incrustans Hall & Whitfield. (Fig. 69.) Devonic. 

 Encrusting other fossils. Astrorhizae with central tubercles 



pierced by pore. 



Upper Devonic of Iowa and elsewhere. 



V. Idiostroma Winchell. 

 Form typically cylindrical, branching or growing in fascicles. 

 Each branch has generally a tabulate tube, while other smaller tab- 

 ulate zobidal tubes with rounded openings are abundant. Radial 

 pillars and concentric laminae distinct. Surface with prominent 

 pointed tubercles often arranged in ridges, or nearly smooth. De- 

 vonic. 



12. I. caespitosum Winchell. Mid-Devonic. 

 Branching irregularly ; branches club-shaped. 



Abundant in the limestones of the Traverse group (Hamilton) in 

 Michigan. 



