HYDROCORALLINES— STROM ATOPOROIDEA. 45 



FlG. 71. Syringostroma densum with horizontal and vertical sections, enlarged 

 (Nicholson, Pal. Ohio). 



17. S. (Syringostroma) centrota Girty. (Fig. 72, a, upper sec- 

 tions.) Lower Devonic. 



Spheroidal, surface with rounded mamelons and minute astro- 

 rhizae. 



Lower Helderberg of New York. 



18. S. (Syringostroma) barretti Girty. (Fig. 72, b, lower sec- 

 tions.) Lower Devonic. 



Hemispheric with flat base, surface without mamelons or astro- 

 rhizae. Laminae flexed in wave-like manner. 

 Lower Helderberg of New York. 





■•:: v- 



Fig. 72. a (upper two), Syringostroma centrotum, tangential and vertical sections ; 

 b (lower two), Syringostroma barretti, tangential and vertical sections (Girty in N. 

 Y. State Mus. Report), enlarged X IO - 



